Determining an equation experimentally: sodium hydrogencarbonate | Starter Quiz | Oak National Academy

The formula for sodium hydrogen carbonate is NaHCO₃. Which of the following statements about sodium hydrogen carbonate are correct?

• The ratio of sodium to oxygen is 1 : 3.

• The ratio of hydrogen to oxygen is 3 : 1.

• The ratio of carbon to sodium is 1 : 1.

• The ratio of oxygen to carbon is 1 : 3.

Answer explanation

Ratios are used to compare two or more quantities. The ratio needs to be written in the same order as in the statement, with the : representing 'to'. For example, the ratio of carbon to oxygen would be written as carbon : oxygen or 1 : 3.

What is the ratio of sodium hydrogen carbonate to water in the following equation? 2NaHCO₃ → Na₂O + 2CO₂ + H₂O.

• 2 : 1

• 1 : 2

• 2 : 2

• 3 : 2

Answer explanation

The coefficient in front of sodium hydrogen carbonate is 2 and there is no coefficient in front of water which means the ratio of sodium hydrogen carbonate to water is 2 : 1.

Which of the following equations shows the correct relationship between moles, mass and relative mass?

• mass = moles × relative mass

• moles = mass × relative mass

• relative mass = mass × moles

• moles = relative mass ÷ mass

Answer explanation

The mass of a substance is equivalent to the moles multiplied by the relative atomic mass or relative formula mass of the substance.

What type of reaction does the following chemical equation represent? CuCO₃ → CuO + CO₂.

• oxidation

• thermal decomposition

• combustion

• neutralisation

Answer explanation

There is one reactant that is broken down into two products using heat, so this is a thermal decomposition reaction.

Calculate the relative formula mass of sodium hydrogen carbonate, NaHCO₃. Relative atomic masses: Na = 23; H = 1; C = 12; O = 16.

Answer explanation

RFM = 23 + 1 + 12 + (3 × 16) = 84

Calculate the mole sof 4.2 g of sodium hydrogen carbonate, NaHCO₃. Relative formula mass of NaHCO₃ = 84.

Answer explanation

moles = mass ÷ relative mass, moles = 4.2 g ÷ 84, moles = 0.05 mol