Download Article
Download Article
Moles are a standard unit of measurement in chemistry that take into account the different elements in a chemical compound. [1] X Research source Often, amounts of compounds are given in grams and need to be converted to moles. This conversion can help give you a clearer picture of the number of molecules you're working with rather than dealing with weight, which can change between molecules. Although the conversion is simple, there are a number of important steps that need to be followed. Using this method, you can learn how to convert grams into moles.
Steps
-
Gather the necessary tools for solving a chemistry problem. Having everything you need easily accessible will simplify the process of solving the assigned problem. You will need the following:
- A pencil and paper. Calculations are easier to solve when you write them out. Be sure to show all your steps to get full credit.
- A periodic table . You will need to be able to find atomic weight of elements using the periodic table.
- A calculator . Calculators are necessary to simplify calculations of complex numbers.
-
Identify the elements in the compound that you need to convert into moles. The first step in calculating molecular mass is identifying each element that composes the compound. It is easy to distinguish elements because abbreviations contain only one or two letters. [2] X Research source
- If a compound is abbreviated with two letters, the first will be capitalized while the second will be lowercase. For example, Mg is the abbreviation for magnesium.
- The compound NaHCO 3 has four elements in it: sodium (Na), hydrogen (H), carbon (C), and oxygen (O).
Advertisement -
Determine the number of atoms that each element contributes to the compound. You must know how many atoms of each element are present to calculate the molecular mass. [3] X Research source The number of atoms each element contributes will be written in a subscript next to the element.
- For example, H 2 O has two atoms of hydrogen and one atom of oxygen.
- If a compound has parentheses followed by a subscript, each element within the parentheses gets multiplied by the number in the subscript. For example, (NH 4 ) 2 S has two atoms of N, eight atoms of H, and one atom of S.
-
Write down the atomic weight of each element. A periodic table is the easiest way to find the atomic weight of an element. Once you locate the element on the table, the atomic weight is usually found underneath the symbol for that element. [4] X Research source
- The atomic weight, or mass, or an element is given in atomic mass units (amu).
- For example, the molecular weight of oxygen is 15.99.
-
Calculate molecular mass. The molecular mass of a substance is calculated as the number of atoms of each element multiplied by the atomic weight of that element. [5] X Research source Knowing the molecular mass is necessary to convert grams to moles. [6] X Research source
- Multiply the number of atoms each element contributes to the compound by the atomic weight of that element.
- Add the total weight of each element in the compound together.
- For example, (NH 4 ) 2 S has a molecular weight of (2 x 14.01) + (8 x 1.01) + (1 x 32.07) = 68.17 g/mol.
- Molecular mass is also referred to as molar mass. [7] X Research source
Advertisement
-
Set up the conversion formula. The number of moles you have of a compound can be calculated by dividing the number of grams of the compound by the molecular mass of the compound. [8] X Research source
- The formula looks like this: moles = grams of compound/molar mass of compound
-
Plug your numbers into the formula. Once you have properly set up the formula, the next step is just putting your calculations into the correct part of the formula. An easy way to check that you have everything in the right place is by the units. Canceling out all the units should leave you with just moles. [9] X Research source
-
Solve the equation. Using a calculator, divide the number of grams by the molar mass. The result is the number of moles in your element or compound. [10] X Research source
- For example, imagine you have 2 g of (NH 4 ) 2 S and you want to convert it to moles. The molecular mass of (NH 4 ) 2 S is 68.17g/mol. Divide 2 by 68.17, and you have 0.0293 moles of (NH 4 ) 2 S.
Advertisement
Calculator, Practice Problems, and Answers
Community Q&A
Search
-
QuestionWhat is the difference between moles and molecules?Community Answer1 mole of a substance is gram molecular mass of that substance, which contains 6.022*10^23 constituent particles (i.e. molecules). 1 mole = 6.022*10^23 molecules.
-
QuestionWhat are the differences in atoms and molecules?Community AnswerAtoms are fundamental elements with 1 nucleus (made up of neutrons and protons), with electrons revolving around the nucleus. Molecules involve bonding between 2+ atoms, so there are 2+ nuclei in a molecule.
-
QuestionHow many moles of CO2 are produced when 0.300 moles of C6H12O6 are fermented?Community AnswerC6H12O6 = 2 C2H6O (alcohol) + 2 CO2, Since 0.3 moles of C6H12O6 produce 2 CO2, then we have produced 2 x 0.3 = 0.6 moles of CO2.
Ask a Question
200 characters left
Include your email address to get a message when this question is answered.
Submit
Advertisement
Video
Tips
- Always include the element or compound name with your answer.Thanks
- If you are asked to show work on your chemistry assignment or test, be sure to identify your answer clearly by circling it or drawing a box around it.Thanks
Submit a Tip
All tip submissions are carefully reviewed before being published
Name
Please provide your name and last initial
Thanks for submitting a tip for review!
Advertisement
Things You'll Need
- Periodic table
- Pencil
- Paper
- Calculator
- Chemistry problem
References
- ↑ https://www.chem.fsu.edu/chemlab/chm1045/mole.html
- ↑ https://uen.pressbooks.pub/introductorychemistry/chapter/molar-mass/
- ↑ https://www.chemteam.info/Mole/MolecWt.html
- ↑ https://chem.libretexts.org/Courses/Anoka-Ramsey_Community_College/Introduction_to_Chemistry/06%3A_Chemical_Composition/6.02%3A_Molecular_Mass_and_Formula_Mass
- ↑ https://www.chemteam.info/Mole/MolecWt.html
- ↑ https://www.chem.purdue.edu/gchelp/howtosolveit/Solutions/determinemolarmass.html
- ↑ https://www.chemteam.info/Mole/MolarMass.html
- ↑ https://www.chemteam.info/Mole/Grams-to-Moles.html
- ↑ https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Fundamentals_of_General_Organic_and_Biological_Chemistry_(LibreTexts)/06%3A_Chemical_Reactions_-_Mole_and_Mass_Relationships/6.02%3A_Gram-Mole_Conversions
About This Article
Article Summary
X
To convert grams to moles, start by multiplying the number of atoms by the atomic weight for each element in the compound. Then, add all of your answers together to find the molar mass of the compound. Finally, divide the number of grams of the compound by the molar mass of the compound to find the number of moles. To learn how to find the number of atoms and the atomic weight for each element, read on!
Did this summary help you?
Thanks to all authors for creating a page that has been read 906,541 times.
Reader Success Stories
- "I currently am taking a high school chemistry course. After about a semester and a half, I had forgotten how to convert from grams to moles. This article was extremely clear, precise, and definitive. Greatly appreciate the extra help." ..." more
Advertisement
"I currently am taking a high school chemistry course. After about a semester and a half, I had forgotten how to convert from grams to moles. This article was extremely clear, precise, and definitive. Greatly appreciate the extra help."
..."
more
"I've been stuck on a chemistry problem for hours, this article was easy to follow along with and really cleared things up for me."
..."
more
"I think is one of the best helpers of all, thank you so much. Visuals help me a lot! Thanks."
"This was amazing and I completely understood it because of the great and helpful pictures!"
"I needed to know this quickly and I did and I just got the idea by watching the pictures."
