Mole Calculation Worksheet

1) How many moles are in 15 grams of lithium?

2) How many grams are in 2.4 moles of sulfur?

3) How many moles are in 22 grams of argon?

4) How many grams are in 88.1 moles of magnesium?

5) How many moles are in 2.3 grams of phosphorus?

6) How many grams are in 11.9 moles of chromium?

7) How many moles are in 9.8 grams of calcium?

8) How many grams are in 238 moles of arsenic?

What are the molecular weights of the following compounds?

9) Na(OH) 12) H3(PO4)

10) H2O 13) Mn2Se7

11) MgCl2 14) (NH¬4)2SO4

15) How many grams are in 4.5 moles of sodium fluoride, NaF?

16) How many moles are in 98.3 grams of aluminum hydroxide, Al(OH)3?

17) How many grams are in 0.02 moles of beryllium iodide, BeI2?

18) How many moles are in 68 grams of copper(II) hydroxide, Cu(OH)2?

19) How many grams are in 3.3 moles of potassium sulfide, K2S?

20) How many moles are in 1.2 x 103 grams of ammonia, NH3?

21) How many grams are in 2.3 x 104 moles of calcium phosphate, Ca3(PO3)2?

22) How many moles are in 3.4 x 105¬ grams of silicon dioxide, SiO2?

23) How many grams are in 1.11 moles of manganese sulfate, Mn3(SO4)7?

1) To find the number of moles in 15 grams of lithium, you need to divide the given mass by the molar mass of lithium. The molar mass of lithium is 6.94 grams/mol.

Number of moles = Mass of lithium / Molar mass of lithium
Number of moles = 15 grams / 6.94 grams/mol

Simplifying the expression:
Number of moles = 2.158 moles

Therefore, there are 2.158 moles in 15 grams of lithium.

2) To find the number of grams in 2.4 moles of sulfur, you need to multiply the number of moles by the molar mass of sulfur. The molar mass of sulfur is 32.06 grams/mol.

Number of grams = Number of moles * Molar mass of sulfur
Number of grams = 2.4 moles * 32.06 grams/mol

Simplifying the expression:
Number of grams = 76.944 grams

Therefore, there are 76.944 grams in 2.4 moles of sulfur.

3) To find the number of moles in 22 grams of argon, you need to divide the given mass by the molar mass of argon. The molar mass of argon is 39.95 grams/mol.

Number of moles = Mass of argon / Molar mass of argon
Number of moles = 22 grams / 39.95 grams/mol

Simplifying the expression:
Number of moles = 0.551 moles

Therefore, there are 0.551 moles in 22 grams of argon.

4) To find the number of grams in 88.1 moles of magnesium, you need to multiply the number of moles by the molar mass of magnesium. The molar mass of magnesium is 24.31 grams/mol.

Number of grams = Number of moles * Molar mass of magnesium
Number of grams = 88.1 moles * 24.31 grams/mol

Simplifying the expression:
Number of grams = 2143.111 grams

Therefore, there are 2143.111 grams in 88.1 moles of magnesium.

5) To find the number of moles in 2.3 grams of phosphorus, you need to divide the given mass by the molar mass of phosphorus. The molar mass of phosphorus is 30.97 grams/mol.

Number of moles = Mass of phosphorus / Molar mass of phosphorus
Number of moles = 2.3 grams / 30.97 grams/mol

Simplifying the expression:
Number of moles = 0.074 moles

Therefore, there are 0.074 moles in 2.3 grams of phosphorus.

6) To find the number of grams in 11.9 moles of chromium, you need to multiply the number of moles by the molar mass of chromium. The molar mass of chromium is 51.99 grams/mol.

Number of grams = Number of moles * Molar mass of chromium
Number of grams = 11.9 moles * 51.99 grams/mol

Simplifying the expression:
Number of grams = 617.181 grams

Therefore, there are 617.181 grams in 11.9 moles of chromium.

7) To find the number of moles in 9.8 grams of calcium, you need to divide the given mass by the molar mass of calcium. The molar mass of calcium is 40.08 grams/mol.

Number of moles = Mass of calcium / Molar mass of calcium
Number of moles = 9.8 grams / 40.08 grams/mol

Simplifying the expression:
Number of moles = 0.244 moles

Therefore, there are 0.244 moles in 9.8 grams of calcium.

8) To find the number of grams in 238 moles of arsenic, you need to multiply the number of moles by the molar mass of arsenic. The molar mass of arsenic is 74.92 grams/mol.

Number of grams = Number of moles * Molar mass of arsenic
Number of grams = 238 moles * 74.92 grams/mol

Simplifying the expression:
Number of grams = 17,835.76 grams

Therefore, there are 17,835.76 grams in 238 moles of arsenic.

9) The molecular weight of Na(OH) can be calculated by adding up the atomic weights of the individual elements.

Atomic weight of Na (sodium) = 22.99 grams/mol
Atomic weight of O (oxygen) = 16.00 grams/mol
Atomic weight of H (hydrogen) = 1.01 grams/mol

Molecular weight of Na(OH) = Atomic weight of Na + Atomic weight of O + 1 * Atomic weight of H
Molecular weight of Na(OH) = 22.99 grams/mol + 16.00 grams/mol + 1.01 grams/mol

Simplifying the expression:
Molecular weight of Na(OH) = 39.00 grams/mol

Therefore, the molecular weight of Na(OH) is 39.00 grams/mol.

Repeat the steps for calculating the molecular weights of the other compounds provided.

To answer these questions, you will need to use the concept of molar mass. The molar mass is the mass of one mole of a substance and is usually expressed in grams per mole (g/mol).

1) To find the number of moles in 15 grams of lithium, you need to know the molar mass of lithium. The molar mass of lithium is approximately 6.94 g/mol. Divide the given mass by the molar mass to calculate the number of moles:
Number of moles = Mass (g) / Molar Mass (g/mol)

2) To find the number of grams in 2.4 moles of sulfur, you also need to know the molar mass of sulfur. The molar mass of sulfur is approximately 32.06 g/mol. Multiply the given number of moles by the molar mass to calculate the mass of sulfur:

Mass (g) = Number of moles x Molar Mass (g/mol)

3) Same as question 1, you need the molar mass of argon, which is approximately 39.95 g/mol. Divide the given mass by the molar mass to calculate the number of moles.

4) Same as question 2, you need the molar mass of magnesium, which is approximately 24.31 g/mol. Multiply the given number of moles by the molar mass to calculate the mass of magnesium.

5) Same as question 1 and 3, you need the molar mass of phosphorus, which is approximately 30.97 g/mol. Divide the given mass by the molar mass to calculate the number of moles.

6) Same as question 2 and 4, you need the molar mass of chromium, which is approximately 51.996 g/mol. Multiply the given number of moles by the molar mass to calculate the mass of chromium.

7) Same as question 1, 3, and 5, you need the molar mass of calcium, which is approximately 40.08 g/mol. Divide the given mass by the molar mass to calculate the number of moles.

8) Same as question 2, 4, and 6, you need the molar mass of arsenic, which is approximately 74.922 g/mol. Multiply the given number of moles by the molar mass to calculate the mass of arsenic.

For questions 9 to 14, you need to calculate the molecular weights of the given compounds.

9) First, calculate the molar mass of Na by multiplying the atomic mass of sodium (22.99 g/mol) by the number of sodium atoms in the formula (1). Then, calculate the molar mass of O by multiplying the atomic mass of oxygen (16.00 g/mol) by the number of oxygen atoms in the formula (1). Finally, add the two molar masses to get the molecular weight of NaOH.

10) The molar mass of water (H2O) can be calculated by adding the molar masses of two hydrogen atoms and one oxygen atom.

11) The molar mass of MgCl2 can be calculated by multiplying the atomic mass of magnesium by 1 and the atomic mass of chlorine by 2, then adding these values together.

12) The molar mass of H3PO4 can be calculated by multiplying the atomic mass of hydrogen by 3, the atomic mass of phosphorus by 1, and the atomic mass of oxygen by 4, then adding these values together.

13) The molar mass of Mn2Se7 can be calculated by multiplying the atomic mass of manganese by 2 and the atomic mass of selenium by 7, then adding these values together.

14) The molar mass of (NH4)2SO4 can be calculated by multiplying the atomic mass of nitrogen by 2, the atomic mass of hydrogen by 8, the atomic mass of sulfur by 1, and the atomic mass of oxygen by 4, then adding these values together.

For questions 15 to 23, you will use the concept of molar mass and the given number of moles or grams to calculate the mass or moles of the compound.

15) Multiply the given number of moles (4.5 moles) by the molar mass of sodium fluoride (41.99 g/mol) to calculate the mass.

16) Divide the given mass (98.3 grams) by the molar mass of aluminum hydroxide (78.00 g/mol) to calculate the number of moles.

17) Multiply the given number of moles (0.02 moles) by the molar mass of beryllium iodide (262.08 g/mol) to calculate the mass.

18) Divide the given mass (68 grams) by the molar mass of copper(II) hydroxide (97.56 g/mol) to calculate the number of moles.

19) Multiply the given number of moles (3.3 moles) by the molar mass of potassium sulfide (110.27 g/mol) to calculate the mass.

20) Divide the given mass (1.2 x 10^3 grams) by the molar mass of ammonia (17.03 g/mol) to calculate the number of moles.

21) Multiply the given number of moles (2.3 x 10^4 moles) by the molar mass of calcium phosphate (310.18 g/mol) to calculate the mass.

22) Divide the given mass (3.4 x 10^5 grams) by the molar mass of silicon dioxide (60.08 g/mol) to calculate the number of moles.

23) Multiply the given number of moles (1.11 moles) by the molar mass of manganese sulfate (1052.09 g/mol) to calculate the mass.

Are you having that much trouble with mols? :-/. Don't sweat it.

Almost every problem comes down to mols. There are two ways to calculate mols.
1. When you have a solution of known molarity, then mols = M x L = ?

2. When you have a mass of something, then mols = grams/molar mass.

#2 will work every problem in this post except for calculating the molar mass and I assume you can add the atomic masses to find the molar mass of the compound listed.

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