asalest 2K
Posts: 41
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Hi,
is there a specific way to know when exactly we need to use Avogadro's #? like key words or concepts that always require us to use it?

Leyna Tran 2D
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One of the times that we use avogadro's number is when the question asks us to convert units of a compound or molecule from moles or grams to "number of atoms" or "number of particles."

Ria Nawathe 2B
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Typically when you need to convert moles of something into atoms or molecules, you would use Avogadro's #. Ex: 0.50 mol C * (6.022E23 atoms C / 1mol C) = 3.0E23 atoms C

VincentLe_1G
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Joined: Wed Sep 30, 2020 10:01 pm

We use Avogadro's number in questions that ask specifically for the "number of objects". For instance, if the problem asks for the number of atoms/particles in an element or molecules in a molecular compound, then you would use Avogadro's number.
If the problem gives you the amount in moles, you would multiply the given amount in moles by Avogadro's number to find the number of objects.
But if it gives the amount in grams, you would have to convert the amount from grams to moles, then multiply by Avogadro's number to find the number of objects.

Crystal Hsueh 2I
Posts: 49
Joined: Wed Sep 30, 2020 9:35 pm

Hi! You would use Avogadro's number if the question was asking you to convert something into moles. For example, if a problem gave you a number of particles and is asking you how many moles there are from those particles, you would divide by Avogadro's number. So a key term/phrase would be "moles" or "how many moles." Just make sure you don't use Avogadro's number if you are given the mass of a substance in grams because then you would need to use molar mass instead.

elena_chen_2B
Posts: 40
Joined: Wed Sep 30, 2020 10:09 pm

Something that helps me remember the concept of Avogadro's number is thinking of it like the number pi. We know that whenever someone says pi, they are always referring to 3.1415... and so on. Likewise, when someone mentions Avogadro's number, they are always referring to 6.022 x 10^23 particles. Avogadro's number is used when converting moles to a number of particles (atoms, molecules, etc). There are 6.022 x 10^23 particles per mole.
Last edited by elena_chen_2B on Mon Oct 05, 2020 12:39 pm, edited 1 time in total.

Anna Yang 2A
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An example of an instance when utilizing Avogadro's # is required would be when asked how many atoms are found in a sample of a substance. For example, a question asking how many atoms are in a sample of 75 grams of silicon would be such occasion. In this way, you would use dimensional analysis: 75g Si * 1 mol Si/28.09g Si * 6.022*10^23 atoms Si/1 mol Si. (28.09g/mol being the molar mass of silicon and 6.022*10^23 atoms being Avogadro's # in terms of atoms per mole) Therefore, grams and moles would cross out, leaving the unit of atoms calculated with Avogadro's number. I believe it can also be used in terms of 6.022*10^23 molecules or formula units per 1 mole of the substance in question.

Katie Le 2K
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Joined: Wed Sep 30, 2020 9:35 pm

You can look up a diagram called "Stoichiometry Island" on Google and it will help you figure out what formulas/constants you need to use to find your answer. Avogadro's # is used when you want to go from moles to atoms or molecules and vice versa.

Nhu Pham-Dis3G
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Joined: Wed Feb 26, 2020 12:15 am

Hi! You can use Avogadro's # when talking about / calculating large numbers. Because 1 mole of any substance equals to 6.022X10^23 g. This creates a universal language that we can use when calculating, and it allows for us to calculate very large numbers without having to deal with their troublesome length. Hope this helps!

Vanshika Bhushan 3A
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Scientists use moles to calculate the number of atoms or molecules in a certain mass of a substance. Avogadro’s number, 6.022 x 10^23 mol^-1, is an absolute number. This means that there are 6.022 x 10^23 particles (molecules, atoms, compounds, etc) in 1 mole. The mass of one mole of a substance is equal to the substance’s molecular weight. So if a problem asks for the number of atoms or molecules, you can use Avogadro’s number to calculate and convert from one unit to another.

Kelly Tran 1C
Posts: 64
Joined: Wed Sep 30, 2020 9:50 pm

You would use Avogadro's Number when converting from moles to a number of atoms/particles, or from the number of atoms/particles to moles. To convert from moles to atoms/particles, you would multiply the given amount of moles by 6.022 x 10^23 (Avogadro's Number). To convert from number of atoms/particles to moles, you would divide the given number by 6.022 x 10^23. Another key word to know when to use Avogadro's Number is "formula units" which is a similar unit to that of atoms/particles.

Gigi Elizarraras 2C
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The most common times I've used Avogadro's number is when I am finding the number of molecules and converting molecules of elements to moles. In one mole there are 6.022e23 particles/molecules so if you know how many moles of an element there are, then you can determine the number of particles.

ex: 2 moles of CO2 -> 6.022E^23 x 2-> 5.86E10 particles in 2 moles of CO2

Tiao Tan 3K
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Joined: Wed Sep 30, 2020 9:59 pm

Avogadro's constant is the NUMBER OF OBJECTS per mole. So if the question is asking,for example, the NUMBER OF ATOMS in an element. We need to use the formula number of atoms in substance = number of substance in moles*Avogadro's constant.

Lorraine Jiang 3C
Posts: 47
Joined: Wed Sep 30, 2020 9:54 pm

Avogadro's constant represents the relationship between the number of particles per mole. So we can use this relationship when the question is asking us to solve for example, how many particles are in x moles of y molecule.

It is also an easy way for you to understand the concept of moles (mol) in chemistry.

Hope it helps!

Elizabeth Kaplan 1D
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Hi! Avogadro's constant is the number of some type of particle! Thus, you know to use Avogadro's constant when the question asks you to find the "number" of some type of particle. Some examples include "the number of atoms", or "the number of molecules". Avogadro's constant is sort of arbitrary, unlike for instance "moles", but it is in general referring to the number of some object.

Mansi Solanki 1K
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Avogadro's constant is meant to symbolize a certain amount of some type of particle and we use this number because it helps us group together otherwise large numbers of atoms, molecules, or some other form of formula units. For instance, in a problem, we know that we have to use Avogadro's constant when we need to convert some number of atoms of a certain element into moles, we would use this constant. Some keywords to look out for would be "atoms," "molecules," or "moles" because often times a problem will specify the way in which the answer is to be expressed.

Alexandra Salata 1J
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Joined: Wed Sep 30, 2020 9:39 pm

Avogadro's number is 6.022×1023 molecules. With Avogadro's number, scientists can discuss and compare very large numbers, which is useful because substances in everyday quantities contain very large numbers of atoms and molecules.

It is used in the equation number of moles = number of particles/avagadro's number

Ralph Zhang 2L
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Many people have already replied with great answers, but to add to this concept I think Avogadro's number can be compared to a "dozen", which is a word used to indicate a specific amount or number.

Joshua Chung 2D
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Joined: Wed Sep 30, 2020 9:32 pm

Avogadro's number is applicable to situations where you need to find or use a number of specific things, such as molecules or atoms (usually a very large quantity of small things).

Daniel Hernandez 3G
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Most of the time, you’ll be required to use Avogadro’s number when being asked to find the “number of atoms” or to find the “number of moles” from a given amount of atoms.

rita_debbaneh3D
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One good rule of thumb is to remember the equation N=n(Na) with N being the amount of something (let's say molecules, atoms, etc.), n being the moles of that something, and Na being Avogadro's constant. If a question gives you a number of molecules or atoms or so forth and asks for the number of moles of this, just rearrange the equation as necessary. By the same token, if they give you the moles of something, just plug in the numbers and you'll get the N. These situations are really straightforward uses of the constant. However, you might get a situation in which you'll have to use the M=n(molar mass) equation before you get to use the original equation (and thus Avogadro's constant). You'll know this if a problem gives you, for example, the mass of a compound and the molar mass and tells you to find the amount of atoms. You'd have to rearrange the second equation and plug in the numbers to find the moles of the compound before using the first equation (and the constant) to find the amount of atoms.

Sheryl Ocampo 1D
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Whenever you're converting to moles or looking for the "number of atoms," you'll be using Avogadro's number

Sukhkiran_Kaur_3F
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Joined: Wed Sep 30, 2020 10:03 pm

Avogadro's number is usually used when converting moles into atoms/molecules.

Kendall_Dewey_2D
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Joined: Wed Sep 30, 2020 10:04 pm

I have found this resource to be helpful in regard to when to use Avogadro's #! https://www.chemteam.info/Mole/Avogadro ... lcsII.html

aashmi_agrawal_3j
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It is used when you are asked to convert to the number of molecules, atoms or particles.

Zoe Staggs 3B
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Joined: Wed Sep 30, 2020 9:33 pm

You would typically use Avogadro's number when a problem asks for the number of particles/atoms in a certain number of moles or grams of a substance. A problem may also give you the number of atoms and ask for the amount of moles or grams in that sample.

ZachMLB963
Posts: 5
Joined: Wed Sep 30, 2020 9:56 pm

Hiya!

Avogadro's Number is used to convert between the count of particles in a substance and moles or grams or liters of said substance.

Thomas Gimeno
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Joined: Wed Sep 30, 2020 9:49 pm

The main purpose of Avogadro's number is to covert between # of particles and mols. The number itself, 6.022x10^23, represents the # of particles in one mole. It super helpful when you either have or need the # of particles but it also comes up in some equations (usually for the purpose of converting).

Brandon Carris
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Avogadro's number is for converting particles to moles. Remember a mole is simply a unit that counts a large number of particles!

Sarah Huang 3A
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To be honest, I have the same question as you! For the most part, I know that when a question, like from Fundamental E, asks you to give an answer in atoms, you would have to use Avogadro's number to convert. Avogadro's number(or constant, whichever you'd like to call it) is a "universal" conversions, usually from things to atoms, or atoms to things. In quantum, we use it to convert something to electrons too!

Sorry I couldn't provide a better explanation, but if I get to it, I'll be sure to let you know. For now, just keep practicing textbook problems and I think you'll get the hang of it!

Yolanda_Xing_3A
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My strategy is that whenever the question contains formula unit or numbers of atoms, I will use the Avogadro’s number. Otherwise, I don’t think it is necessary.

Grace_Remphrey_2G
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