How To Find Moles From Volume And Concentration

Many solutions contain one component, called the solvent, in which other components, called solutes, are dissolved. An aqueous solution is one for which the solvent is water. The concentration of a solution is a measure of the relative amount of solute in a given amount of solution.

Concentrations may be measured using various units, with one very useful unit being molarity, defined as the number of moles of solute per liter of solution. The solute concentration of a solution may be decreased by adding solvent, a process referred to as dilution. The dilution equation is a simple relation between concentrations and volumes of a solution before and after dilution. An aqueous solution consists of at least two components, the solvent and the solute . Usually one wants to keep track of the amount of the solute dissolved in the solution. One could do by keeping track of the concentration by determining the mass of each component, but it is usually easier to measure liquids by volume instead of mass.

Molarity is defined as the number of moles of solute divided by the volume of the solution in liters. For example, the known molecular weight of a chemical can be used along with the desired solution volume and solute concentration to determine the mass of chemical needed to make such a solution. As with w/v solutions, we weigh out a specific amount of chemical when making a molar solution. Unlike w/v solutions, the amount to weigh depends on the molecular weight (m.w.) of the substance in grams per mole (g/mol). In order to calculate the desired mass of solute you will need to know the formula weight.

Formula weights are usually printed on the label and identified by the abbreviation f.w. Formula weight is the mass of material in grams that contains one mole of substance, and may include inert materials and/or the mass of water molecules in the case of hydrated compounds. For pure compounds the formula weight is the molecular weight of the substance and may be identified as such. The concentration of a substance is the quantity of solute present in a given quantity of solution. Concentrations are usually expressed as molarity, the number of moles of solute in 1 L of solution. Figure 4.6 "Preparation of a Solution of Known Concentration Using a Solid Solute" illustrates this procedure for a solution of cobalt chloride dihydrate in ethanol.

Because the solute occupies space in the solution, the volume of the solvent needed is almost always less than the desired volume of solution. For example, if the desired volume were 1.00 L, it would be incorrect to add 1.00 L of water to 342 g of sucrose because that would produce more than 1.00 L of solution. As shown in Figure 4.7 "Preparation of 250 mL of a Solution of (NH", for some substances this effect can be significant, especially for concentrated solutions. It is important to note that the molarity is defined as moles of solute per liter of solution, not moles of solute per liter of solvent.

This is because when you add a substance, perhaps a salt, to some volume of water, the volume of the resulting solution will be different than the original volume in some unpredictable way. To get around this problem chemists commonly make up their solutions in volumetric flasks. These are flasks that have a long neck with an etched line indicating the volume.

The solute is added to the flask first and then water is added until the solution reaches the mark. The flasks have very good calibration so volumes are commonly known to at least four significant figures. To calculate the molarity of a solution, the number of moles of solute must be divided by the total liters of solution produced. Suppose that someone has already worked out the details, so all that you have to do is read a formula and make a solution. We can usually assume that a solution is to be aqueous unless stated otherwise. What about the concentration of the substance to be added?

Common ways of describing the concentrations of solutions are weight-in-weight, weight-in-volume, volume-in-volume, and molarity. Less commonly used descriptions include normality and molality. A quantity of solute is measured out, mixed with solvent, and the volume is brought to some final quantity after the solute is completely dissolved. That is, solutions are typically prepared volumetrically.

Because solutes add volume to a quantity of solvent, this method of preparation of solutions is necessary to ensure that an exact desired concentration is obtained. To calculate the molarity of a solution, the number of moles of solute must be divided by the total liters of the solution produced. V is volume of solution in liters in which the indicated mass of solute must be dissolved to make the desired molar concentration . Note that V is the final or total volume of solution after the solute has been added to the solvent. A disadvantage of describing formulas as w/v (%) is that the description says nothing about the actual concentration of molecules in solution.

What if we want equal amounts of two chemicals to be mixed together, so that for each molecule of substance #1 there is a single molecule of substance #2? The same amount in grams will likely not contain the same number of molecules of each substance. For example, you may work with a chemical that can be in one of several forms of hydration. Calcium chloride can be purchased as a dry chemical in anhydrous form, so that what you weigh out is nearly all pure calcium chloride.

On the other hand you may have a stock of dry chemical that is hydrated with seven water molecules per molecule of calcium chloride. The same mass of this chemical will contain fewer molecules of calcium chloride. When we are interested in the actual concentration of molecules of a chemical in solution, it is better to have a universal measurement that works regardless of how the chemical is supplied. As long as the molecular weight is known, we can describe a solution in the form of moles per liter, or simply molar . While molality can be quite useful as a measurement of concentration, it isn't too convenient for converting to molarity.

The reason is that we usually don't know how much volume the solute is going to occupy in the solution. For example, when 900 ml of distilled H2O is mixed with 100 ml of ethanol , the total volume of the resulting aqueous solution will be less than 1 liter. The ethanol molecules are capable of organizing H-bonded water molecules tightly around them, resulting in a smaller volume than the combined volumes of the separate components.

In the solid, crystalline form glucose molecules are also ordered into a three dimensional array, as in the case of the NaCl crystal lattice discussed above. However, unlike in the case of NaCl, in which the compound breaks apart into smaller components , the glucose molecule remains intact as a single molecular unit in solution. The figure below is a schematic of the glucose molecule dissolved in water. Each glucose molecule is surrounded by a certain number of water molecules; therefore in solution, the glucose solid broke apart, but the glucose molecules themselves remained intact. Note that the definitions of molarity, molality, and mole fraction are the same for both molecular and nonmolecular solutions. You will learn more about interactions between molecules in Chemistry 111.

A schematic of the glucose molecule in aqueous solution. Concentrations are often reported on a mass-to-mass (m/m) basis or on a mass-to-volume (m/v) basis, particularly in clinical laboratories and engineering applications. Each measurement can be expressed as a percentage by multiplying the ratio by 100; the result is reported as percent m/m or percent m/v. For aqueous solutions at 20°C, 1 ppm corresponds to 1 μg per milliliter, and 1 ppb corresponds to 1 ng per milliliter. These concentrations and their units are summarized in Table 4.1 "Common Units of Concentration".

Molality is an intensive property of solutions, and it is calculated as the moles of a solute divided by the kilograms of the solvent. Unlike molarity, which depends on the volume of the solution, molality depends only on the mass of the solvent. Since volume is subject to variation due to temperature and pressure, molarity also varies by temperature and pressure. In some cases, using weight is an advantage because mass does not vary with ambient conditions. For example, molality is used when working with a range of temperatures. A one percent solution is defined as 1 gram of solute per 100 milliliters final volume.

For example, 1 gram of sodium chloride, brought to a final volume of 100 ml with distilled water, is a 1% NaCl solution. To help recall the definition of a 1% solution, remember that one gram is the mass of one milliliter of water. The mass of a solute that is needed in order to make a 1% solution is 1% of the mass of pure water of the desired final volume. Examples of 100% solutions are 1000 grams in 1000 milliliters or 1 gram in 1 milliliter. Perhaps the easiest way to describe a solution is in terms of weight-in-weight (w/w). The weight of the solute relative to the weight of the final solution is described as a percentage.

How To Find Moles From Volume Without Concentration For example, suppose you have a dye that is soluble in alcohol. Rather than write the instructions, "take 3 grams dye and mix with 97 grams absolute alcohol," you can describe the solutions simply as 3% dye in absolute alcohol. The formula applies to any volume of solution that might be required. Three grams dye plus 97 grams alcohol will have final weight of 100 grams, so the dye winds up being 3% of the final weight. Note that the final weight is not necessarily equal to the final volume.

Aqueous weight-in-weight solutions are the easiest to prepare. Since 1 milliliter of water weighs one gram, we can measure a volume instead of weighing the solvent. A very common use of w/w formulas is with media for the culture of bacteria. Such media come in granular or powdered form, often contain agar, and often require heat in order to dissolve the components. Microbiological media, especially when they contain agar, are difficult to transfer from one vessel to another without leaving material behind. They coat the surfaces of glassware, making quite a mess.

Using a w/w formula the media and water can be mixed, heated, then sterilized, all in a single container. Very little material is wasted and there is less of a mess. Molarity is moles of solute divided by liters of solution, not solvent. Here we've just calculated an approximate molarity, but the volume effect of adding a small amount of solute to water is usually small, so this calculation probably isn't too bad. The molarity is the number of moles of solute per liter of solution.

Molarity is defined as the number of moles of solute per unit volume. The molarity is reported as M , which is mol of solute/L of solution. Molarity is temperature dependent as the volume of the density of a solution typically changes with temperature. The definition of molarity means that you can find the molarity of a solution if you know the total number of moles of the solute and the total volume of the solution. So, in order to calculate the concentration of a solution , you need to divide moles of solute by total volume.

In an ionic solution, ionic strength is proportional to the sum of the molar concentration of salts. Molar concentration is a measure of the concentration of a chemical species, in particular of a solute in a solution, in terms of amount of substance per unit volume of solution. In chemistry, the most commonly used unit for molarity is the number of moles per liter, having the unit symbol mol/L or mol⋅dm−3 in SI unit. A solution with a concentration of 1 mol/L is said to be 1 molar, commonly designated as 1 M. To avoid confusion with SI prefix mega, which has the same abbreviation, small caps ᴍ or italicized M are also used in journals and textbooks.

The molarity calculator calculates the mass of compound required to achieve a specific molar concentration and volume. To dilute a solution of known molarity, please use the Solution Dilution Calculator. To dilute a solution of concentrated acid or base of known w/w% strength, please use the Acid & Base Molarity Calculator. We then convert the number of moles of solute to the corresponding mass of solute needed.

Both terms are used to express the concentration of a solution, but there is a significant difference between them. While molarity describes the amount of substance per unit volume of solution, molality defines the concentration as the amount of substance per unit mass of the solvent. In other words, molality is the number of moles of solute per kilogram of solvent . The units of molar concentration are moles per cubic decimeter. They are noted as mol/dm³ as well as M (pronounced "molar").

In many older books or articles, you can find different units of molar solutions – moles per liter (mol/l). Remember that one cubic decimeter equals to one liter, so these two notations express the same numeric values. When we describe a concentration as a percentage without specifying the type of formula, we imply that the solution is to be made using the weight-in-volume (w/v) method. As with w/w, weight-in-volume is a simple type of formula for describing the preparation of a solution of solid material in a liquid solvent.

A mole fraction, as the name implies, is a comparison of the number of moles in solution. It is found by taking the number of moles of solutes divided by the total number of moles (solutes + solvent). So you are not confused with similar chemical terms, keep in mind that molarity means exactly the same as molar concentration . It is defined as the number of moles of a substance or solute, dissolved per liter of solution (not per liter of solvent!).

This molarity calculator is a tool for converting the mass concentration of any solution to molar concentration . You can also calculate the mass of a substance needed to achieve a desired molarity. This article will provide you with the molarity definition and the molarity formula. This figure ( → ) shows how to make an X-molar solution, where X is the desired molar concentration.

The solute is dissolved in a smaller volume of solvent, then the total volume is adjusted to the final desired amount. The amount in moles of solute or the mass in grams of solute in a given volume of solution can be calculated from its concentration in mol/dm³. Molecules in a litre or even a cubic centimetre is enormous, it has become common practice to use what are called molar, rather than molecular, quantities.

A mole is the gram-molecular weight of a substance and, therefore, also Avogadro's number of molecules (6.02 × 1023). Thus, the number of moles in a sample is the weight of the sample divided by the molecular weight of the substance; it is also the number of molecules in the sample divided by Avogadro's number. Concentration in moles per litre (i.e., molarity) is usually designated by the letter M.

Molarity is a unit of concentration, measuring the number of moles of a solute per liter of solution. The strategy for solving molarity problems is fairly simple. This outlines a straightforward method to calculate the molarity of a solution. To find the concentration of this new solution you need to convert from grams to moles. This requires the use of the molar mass (given in grams/mole) of the NaCl. The molar mass of a substance is found by adding together the molar mass of the individual components.

Now you should have a good understanding of solutions and the solvation process for ions in aqueous solutions. You need to be comfortable with using molarity, molality and mole fractions. Also you should know the definitions pertaining to solutions. When discussing solutions, we typically talk about the solution's concentration.

Apple Watch Series 6 Vs 7 Vs Se

The Apple Watch Series 7 offers the same suite of sensors as the Series 6. These include an accelerometer, a gyroscope, a heart rate sensor, a barometer, an always-on altimeter, a compass, an SpO2 sensor, and a VO2 max sensor. These sensors have a host of health and fitness tracking features, including blood oxygen monitoring, heart rate monitoring, sleep tracking, fall detection, workout tracking, and more.

Its apps are basic, although it has seen an upgrade from monochrome to colour touchscreen. The S7 SiP with 64-bit dual-core processor is up to 20% faster than the S5 in Apple Watch SE.12 The always-on altimeter detects your elevation in real time. The Apple Watch Series 7 builds on the SE's feature set, with a larger display that curves around the edges (that's always-on), along with blood oxygen monitoring, faster charging and exclusive watch faces. While the 3 and SE have aluminium cases, the 7 has options in stainless steel and titanium, too, with more colour and band options. While the Apple Watch Series 3 is an older version , it is still a great smartwatch with fitness and health features at a low price point. Its display is much smaller and not as bright as the other two Apple Watch versions, with a lower resolution.

It gives high and low heart-rate notifications and can check on irregular heart rhythms. It has built-in GPS, optical heart sensor, gyroscope, altimeter, speaker and microphone . Battery life on both is a full day's usage, so overnight charges are required, but you won't be buying the series 6 for extra battery life.

Although the SE doesn't have ECG or blood oxygen monitoring, it has the same heart rate capabilities and neat features like Breathe, a one-minute mindfulness app, as the series 6. So, the difference between the two generations of Apple's smartwatches boils down to the importance placed on the larger display, the reduced charging time, water-and-dust resistance, and color options. If one has already made up one's mind, there is no persuading otherwise.

The Series 7 features several advanced health-tracking features Apple introduced on the Series 6 that you don't get on the SE, including sensors for blood oxygen saturation and electrocardiogram readings. The ECG function checks for signs of atrial fibrillation , an irregular heart rhythm that can lead to blood clots, stroke, heart failure, and other serious complications. Those features, plus the larger screen and always-on display option, justify the Series 7's $120 markup from the SE. After hours, differences in sleep tracking are also worth considering. We tend to find sleep tracking on Apple Watches basic at best, especially compared to companies like Fitbit.

However, if you choose the Series 6, you can use the SpO2 sensor to track your blood oxygen while you snooze. Unfortunately, it's not a clinically validated sensor, so it can't alert you to any potential signs of sleep apnea. As for fitness tracking, both devices automatically track a variety of workouts and can manually track many others. Either one tracks your steps, resting and active heart rate, active and resting energy burn, standing minutes, distance, floors climbed, and more.

Speaking of the battery, the Series 7 promises the same runtime as its predecessor, which is to say, about 18 hours. I generally found myself getting about half a day more from the new watch than the SE, despite the lack of an Always On display on the SE. The Series 7 usually stuck around for a day and a half, almost two, with the screen set to Always On, and tracking between three and five workouts.

I also used the device to send plenty of messages and map my walks while I ran errands with the GPS on. That endurance is impressive given the larger screen, but it's worth noting that I haven't used the watch for sleep tracking yet. Now, although Apple will not officially sell the Apple Watch 6, users can still buy the previous-gen Apple Watch from third-party resellers until stocks last.

So, which one should you get if you are in the market for an Apple Watch? Well, if you want the latest and greatest from Apple, we recommend you go for the latest Apple Watch 7. The larger display, dust resistance, and faster charging are reasons enough to convince prospective buyers. Otherwise, if you don't care much about these minor upgrades and just want the Apple Watch experience, go with Apple Watch 6, which will now sell at reduced prices. Apple has also made some significant improvements to battery life and charging on the Apple Watch Series 7. The company claims that the new smartwatches offer 18-hour all-day battery life, along with 33% faster charging than the previous model.

The major health and fitness features to consider when comparing the Apple Watch SE vs the Apple Watch Series 6 are sensors. Blood oxygen monitoring and electrocardiogram sensors are absent from the SE model, so if these are deal-breakers, you'll need to upgrade to the Series 6. That being said, the Apple Watch SE does still offer all-day heart rate monitoring. Like the Series 6, it can tell you if you have a heart rate that is abnormally high or low, and both devices will also notify you if they detect irregular heart rates. The Series 6 uses an upgraded sensor, so it's the leader if you want the best in terms of accuracy.

It's worth noting that all of these features - except the always-on altimeter - can be found on the Series 4 and 5 too. Overall, the ‌Apple Watch Series 7‌ is a minor upgrade over the Apple Watch Series 6, offering larger displays and casing sizes, new color options, improved durability, the S7 chip, and faster charging. These features are mostly iterative improvements rather than major reasons to upgrade, and the Series 7 does not add any new functionality. While you shouldn't expect a bump in battery life for the Series 7, it does juice up faster than earlier models thanks to a new charging architecture and a Magnetic Fast Charger USB-C Cable. Apple says it charges 33% faster than the Series 6—just 45 minutes of charging will take the watch from dead to 80% battery life.

And eight minutes on the charger offers eight hours of juice for overnight sleep tracking. Compared to the Watch SE though, the Series 6 only adds an always-on display, ECG, blood oxygen monitoring, a faster processor and the U1 chip. In terms of the Series 7, a bigger display is added, but otherwise the features are almost identical to the Series 6. All the Watch models being compared here have built-in GPS, optical heart rate sensor, speaker, microphone, water resistance up to 50 metres, emergency SOS, gyroscope and an ambient light sensor.

Secondly, in the case of the Series 7 , the Digital Crown has an electrical heart rate sensor built into it, which is in addition to the optical heart rate sensor on the underside of the watch. The Watch Series 7 also has a blood oxygen sensor, like the Series 6, and it has reduced bezels surrounding the display, as well as an IPX6 dust resistance. The ‌Apple Watch Series 7‌ is an improvement over the previous Series 6 model, offering a larger display, improved durability, and faster charging. If you are particularly interested in health tracking, the larger display, fast charging, or simply like a particular casing and color combination, the ‌Apple Watch Series 7‌ will be the best model for you. This older model offers substantially fewer features and has a smaller screen. The Apple Watch Series 3 is still a capable device, with 8GB of storage, water-resistance up to 50 meters, an altimeter, Emergency SOS, and an optical heart sensor.

Functionally, it is more pared back than the ‌Apple Watch SE‌, being thicker with larger bezels. There is also the Apple Watch Series 3, which Apple sells for $199. The Apple Watch Series 7 offers a number of upgrades and improvements on 2020's Series 6, offering a larger display with bigger casing sizes, faster charging, and the S7 chip, for a price starting at $399.

Like the Series 6, the Series 7 features a blood oxygen sensor and an EKG function designed to detect unusual heart rhythms. The Series 7 ships with a new cable that allows for faster charging. The Series 7 will use WatchOS 8 which comes with a whole set of health and fitness tracking features, metrics, and watch faces. Meanwhile, the Workouts app lets you find new workout modes like Tai Chi and pilates. The Fitness+ app boasts seven new high-intensity workout plans, and there are motivational playlists to accompany the Artist Spotlight series. The Series 7 offers the same 18-hour battery life as the 6, but with 33% faster charging.

Because I don't typically sleep in my Watch, a full charge gives me two full days of use. Unlike the 6, I don't have to wait as long for the Watch to be ready to go. Apple watch SE looks identical to series 6 and works largely the same, though it lacks some of the extra features and more powerful processor on the flagship watch. The display is not always-on, as on series 6, so to see the time, or whatever's on the screen, you need to raise your wrist.

The Apple watch is completely reliable at illuminating the screen with the slightest movement, unlike some rival gadgets, but it's not quite as slick as series 6. But in everyday use, there's precious little difference between the two models, and the SE is more than £100 cheaper. Noise monitoring is a feature that sends you alerts when the racket around you is loud enough to potentially damage your hearing. The latest processor is only found in series 6 (Apple watch SE uses last year's chip, which is still pretty nippy). And if you are tracking your sleep, then you'll need to wear the watch at night and recharge it in the morning. Though both SE and series 6 can do this, the battery on the series 6 recharges more quickly.

In terms of choice of design, health features and sheer power, Apple watch series 6 is head and shoulders above the SE – and every other smartwatch available. The Apple Watch Series 7 and Apple Watch SE also differ in the available health tracking features. Both offer a heart rate sensor that can measure your current heart rate and provide high and low heart rate notifications. Either watch will also provide irregular heart rate notifications. Thanks to the larger display on the Series 7, it also offers a full keyboard with QuickPath for replying to messages.

At its September special event in 2021, Apple introduced the Apple Watch Series 7. The Series 7 replaces the Apple Watch Series 6, which was announced in September of 2020, as the company's flagship wearable. The Apple Watch Series 7 offers a number of upgrades and improvements on 2020's Series 6, offering a larger display with bigger casing sizes, faster charging, and the S7 chip, for a... The ‌Apple Watch Series 7‌ starts at $399, while the ‌Apple Watch SE‌ is priced much more competitively at $279.

As these two models share many key features, including design, water resistance, and an optical heart sensor, it may not be immediately obvious which model is better for you. Is it worth purchasing the cheaper model with fewer features? Our guide answers the question of how to decide which of these two Apple Watch models is best for you. The Series 6 also has the sensor that enables an EKG function designed to detect unusual heart rhythms.

Is a mid-range model, based on the Apple Watch Series 4, but missing some of the top-end Watch's features. That said, it has a larger display than the Series 3 - though not quite as big as the new Series 7 - along with an ECG monitor and a faster processor, but not an always-on display function. It has a built-in compass, always-on altimeter, and fall detection on top of everything the Watch 3 has. Apple is known for its smartwatches, and Fitbit for itsactivity trackers and fitness and health smartwatches. But the boundaries and functions are getting blurred with Fitbit adding apps and lovely touchscreens to its trackers, and Apple adding more health features to its Watch. Though the differences between the Series 6 and 7 seem minor, it's worth a reminder that most people who own last year's model likely aren't looking to upgrade yet anyway.

For anyone else who's looking for a new smartwatch, the Series 7 will be a satisfying purchase, especially if you've never used one before. It's not the best at sleep-tracking, though, so if that's a priority you might prefer a Fitbit. Despite its relatively high starting price of $400, what Apple offers is currently the best in the market, especially for the iOS ecosystem. The Series 7 is powered by Apple's S7 SiP with 64-bit dual-core processor just like the S6, so no huge change there. It also has the same sensor array on the back, ready to measure heart rate and blood oxygen and take an electrocardiogram reading. There's a new fall-detection feature that works during workouts and when cycling, and through WatchOS 8, the Series 7 will measure respiratory rate during sleep.

Other than this, the Apple Watch 7 display is also 70% brighter vs the Apple Watch 6 display in terms of the always-on display. That means you will be able to check the time more easily when idle in comparison to the previous-gen model. Plus, Apple has redesigned some of the UI elements on the Series 7 to utilize the larger screen area. For instance, you now have larger on-screen buttons, can read long texts in one go, new in-depth activity complications, and quirky watch faces to match the larger curved display on the Series 7. Moreover, unlike the previous-gen model, Series 7 features a full keyboard with swipe support to input texts.

The latest watchOS8 runs on the Series 3, 4, 5, 6, 7, and SE models. This means they all provide similar experiences, apart from any additional features on the later watches (e.g. ECD functions or fall detection sensors). The Apple Watch Series 7 offers a new QWERTY keyboard and QuickPath to help users type and send messages easier. With excellent app support, a stylish design, and plenty of fitness, health, and sleep tracking features, the value is hard to argue. You care about having the latest and best design on your wrist.

The Series 7 also boasts the best health features Apple has to offer, and fast charging makes the short battery life easier to live with. This is Apple's most powerful smartwatch yet and it features upgrades like a bigger screen, dust resistance, faster charging and more. But taking a deeper look at the differences between the Watch Series 7 andSeries 6, it doesn't seem like a major upgrade.

We tell you what has changed and what remains the same in this detailed comparison. For users who already have an Apple Watch Series 6, the Series 7 probably does not offer enough to warrant upgrading unless you particularly want a larger display, faster charging, or improved durability. The design changes and new features are iterative rather than transformative, and there are no new major capabilities, so many Series 6 users may prefer to wait a little longer to upgrade. The Apple Watch Series 7 offers blood oxygen monitoring just like the Series 6 did last year, and it also has an electrical heart sensor. Both of those features are missing from the Apple Watch SE, but pretty much every other health feature is on the cheaper model.

The ‌Apple Watch SE‌ has an optical heart sensor to monitor heart rate, and can give notifications about high and low heart rate, and as well as irregular heart rhythm. The lower-cost model can also still perform emergency SOS, fall detection, and noise monitoring, just like the ‌Apple Watch Series 7‌. In September 2021, Apple introduced the Apple Watch Series 7, featuring larger displays, improved durability, and faster charging. This came one year after Apple unveiled the Apple Watch SE, a low-cost Apple Watch option that still offers many of the Apple Watch features that have made the device so popular over the years.

This model has fewer features than the Apple Watch Series 6, but is a lower-cost option with many of the aspects that have made the Apple Watch so popular over the years. The ‌Apple Watch SE‌ does not have an always-on display, ECG, or blood oxygen monitoring, but it does contain the same S5 chip as the Series 5 and the same always-on altimeter as the Series 6. If you find that you have little time to charge your Apple Watch during the day, the Series 7's faster charging could be an important reason to upgrade for you.

Even so, both devices still have the same "all-day" 18-hour battery life and will need to be recharged every day. The Apple Watch SE, in contrast to its more expensive counterparts, packs an optical heart rate sensor, fall detection, an always-on altimeter. Unlike the last few generations of flagship wearables, it does not have a blood oxygen sensor or an electrocardiogram. The Series 7 does usher in a new feature that logs your respiration rate while you sleep, and then tells you your breath-per-minute rate the next morning. This means they're less likely to sway your decision on whether to get the Series 7 if you already have an Apple Watch. The main things exclusive to the Series 7 are the Modular Duo and Contour watch faces, larger font sizes and buttons, and the QWERTY keyboard.

The main difference between the Apple Watch designs is that the Series 7 features an electrical heart rate sensor built into it and an added optical heart rate sensor too. The 6 and 7 both have a SpO2 sensor and reduced bezels around the main display. On the inside, the Apple Watch 7 boasts a 70% brighter Always-On display, IP6X dust protection, and similar water-resistance as previous models, as well as greater durability. There is no difference in battery life , however, the battery recharges 33 per cent quicker. The Apple Watch 3 does not have all of the above – no fall detection, wireless charging or cellular option. It's also slightly smaller in screen sizes, less sophisticated, and has fewer supported apps.