Mole calculations, empirical and molecular formulae

Question 1 of 10

The molar mass of potassium hydroxide, KOH, is ___ g/mol. (H = 1, C = 12, N = 14, O = 16, Na = 23, Mg = 24, Al = 27, S = 32, Cl = 35.5, K = 39, Ca = 40, Fe = 56, Cu = 64)

Question 2 of 10

One mole of a substance contains

Question 3 of 10

A compound contains 92.3% carbon, 7.7% hydrogen by mass. Its relative molecular mass is 78. (C = 12, H = 1, O = 16) (a) Find its empirical formula. (b) Find its molecular formula.

Question 4 of 10

A compound contains 85.7% carbon, 14.3% hydrogen by mass. Its relative molecular mass is 56. (C = 12, H = 1, O = 16) (a) Find its empirical formula. (b) Find its molecular formula.

Question 5 of 10

The empirical and molecular formulae of water are the same.

Question 6 of 10

The molecular formula of a compound with empirical formula CH₂ and molar mass 42 g/mol is

Question 7 of 10

The molar mass of iron(III) oxide, Fe₂O₃, is ___ g/mol. (H = 1, C = 12, N = 14, O = 16, Na = 23, Mg = 24, Al = 27, S = 32, Cl = 35.5, K = 39, Ca = 40, Fe = 56, Cu = 64)

Question 8 of 10

The molar mass of CaCO₃ is 100 g/mol.

Question 9 of 10

The unit of molar mass is

Question 10 of 10

How many moles are in 11.2 g of potassium hydroxide, KOH?