Units 3 & 4 CMT Review OL

Front

Identify the coefficients of the following equation: PCl5 + ___ H2O → ___ HCl + ___ H3PO4

Back

1, 4, 5, 1

Front

What percentage of the total atomic mass of magnesium bromide (MgBr2) is composed of magnesium?

Back

13%

Front

A formula with the lowest whole number ratio of elements in a compound is called?

Back

Empirical Formula

Front

Find the percent composition of N2S2.

Back

N: 30.4% S: 69.6%

Front

Which has more moles of particles: 12.0 g carbon, 6.94 g lithium, 10.81 g boron, or all have the same number of moles?

Back

All have the same number of moles.

Front

What is the definition of a coefficient in a chemical equation?

Back

A coefficient is a number placed in front of a chemical formula to indicate the number of molecules or moles of that substance.

Front

What is the empirical formula of a compound?

Back

The empirical formula is the simplest whole number ratio of elements in a compound.

Front

How do you calculate percent composition of an element in a compound?

Back

Percent composition = (mass of element in 1 mole of compound / molar mass of compound) x 100%.

Front

What is the molar mass of magnesium bromide (MgBr2)?

Back

Molar mass = 24.31 g/mol (Mg) + 2 x 79.90 g/mol (Br) = 184.11 g/mol.

Front

What is the significance of the empirical formula in chemistry?

Back

It provides the simplest ratio of elements in a compound, which is useful for understanding its composition.