Note: Moles to grams, or grams to moles you will need to use molar mass (g/mol).

1) How many moles are in 20.2 g HCl?

2) How many grams are in 2 moles of HCl?

Note: When converting from moles to molecules, you need the following: 1 mole = 6.022 x 1023 molecules

3) How many molecules are in 23 moles of Sodium?

4) How many moles are in 8.022 x 1026 molecules of NaCl?

Note: 1 mole = 22.4 L

5) How many moles are in 5 Liters of H2 gas?

6) How many Liters are in 5 moles of H2 gas?

Multiple Conversions in one problem.

7) How many grams of HCl will be produced with 16.2 grams of H2 and excess Cl2? (H2 + Cl2 - > 2HCl)

8) How many Liters are there in 46 g of Cl2 gas?

1) Answer is: there is 0,554 moles in 20,2 grams of HCl.

m (HCl) = 20,2 g.

M (HCl) = 1,01 g/mol + 35,45 g/mol.

M (HCl) = 36,46 g/mol.

n (HCl) = m (HCl) : M (HCl).

n (HCl) = 20,2 g : 36,46 g/mol.

n (HCl) = 0,554 mol.

n - amount of substance.

2) Answer is: there is 72,92 grams in 2 moles of HCl.

n (HCl) = 2 mol.

M (HCl) = 1,01 g/mol + 35,45 g/mol.

M (HCl) = 36,46 g/mol.

m (HCl) = n (HCl) · M (HCl).

n (HCl) = 2 mol · 36,46 g/mol.

n (HCl) = 72,92 g.

M - molar mass.

3) Answer is: there is 1,385·10²⁵ atoms ins 23 moles of sodium.

n (Na) = 23 mol.

N (Na) = n (Na) · Na.

N (Na) = 23 mol · 6,022·10²³ 1/mol.

N (Na) = 1,385·10²⁵.

Na - Avogadro number.

N - number of particles.

4) Answer is: there is 1332 moles in 8,022·10²⁶ molecules of NaCl.

N (NaCl) = 8,022·10²⁶.

N (NaCl) = n (Na) · Na.

n (NaCl) = N (NaCl) : Na.

n (NaCl) = 8,022·10²⁶ : 6,022·10²³ 1/mol.

n (NaCl) = 1,332·10³ mol = 1332 mol.

Na - Avogadro number.

N - number of particles.

5) Answer is: there is 0,223 moles in 5 liters of hydrogen gas.

V (H₂) = 5 L.

n (H₂) = ?.

Make proportion: 5 L : n (H₂) = 22,4 L : 1 mol.

22,4 · n (H₂) = 5 L · 1 mol.

n (H₂) = 0,223 mol.

V - volume of hydrogen gas.

6) Answer is: there is 112 liters in 5 moles of hydrogen gas.

n (H₂) = 5 mol.

V (H₂) = ?.

Make proportion: 5 mol : V (H₂) = 1 mol : 22,4 L

22,4 L · 5 mol = V (H₂) · 1 mol.

V (H₂) = 112 L.

V - volume of hydrogen gas.

n - amount of substance.

7) Answer is: there is 584,81 grams of HCl.

Chemical reaction: H₂ + Cl₂ → 2HCl.

m (H₂) = 16,2 g.

n (H₂) = m (H₂) : M (H₂).

n (H₂) = 16,2 g : 2,02 g/mol.

n (H₂) = 8,02 mol.

From chemical reaction: n (H₂) : n (HCl) = 1 : 2.

n (HCl) = 16,04 mol.

m (HCl) = 16,04 mol · 36,46 g/mol.

m (HCl) = 584,81 g.

8) Answer is: there is 14,51 liters in 46 g of Cl₂ gas.

m (Cl₂) = 46 g.

n (Cl₂) = m (Cl₂) : M (Cl₂).

n (Cl₂) = 46 g : 70,9 g/mol.

n (Cl₂) = 0,648 mol.

Make proportion: 0,648 mol : V (Cl₂) = 1 mol : 22,4 L.

V (Cl₂) = 0,648 mol · 22,4 L : 1 mol.

V (Cl₂) = 14,51 L.