Chemical Formulae, Equations and Calculations Part 1

What is the unit used to measure the amount of substance in chemistry?

A student reacts 8.0 g of hydrogen with excess oxygen to make water, according to the equation:

The student obtains 70.0 g of water. (Ar: H = 1, O = 16)

A compound contains 2.70 g of aluminum and 4.80 g of chlorine. (Ar: Al = 27, Cl = 35.5)

Calculate the empirical formula of this compound.

A student heats a crucible containing a strip of magnesium in air and finds an increase in mass after the reaction.

Explain why the mass increases, and how this method helps to determine the formula of magnesium oxide.

The following table shows substances involved in a chemical reaction:

Complete the table with the correct state symbols and write the balanced chemical equation including state symbols for the reaction where iron(III) oxide reacts with carbon monoxide to produce iron and carbon dioxide.

State the relative formula mass (Mr) of water, H2O. (Ar: H = 1, O = 16)

Answer the questions about carbon dioxide, CO2.

Calculate the number of moles in 12.0 g of magnesium oxide, MgO. (Ar: Mg = 24, O = 16)

Write the balanced chemical equation, including state symbols, for the reaction between sodium hydroxide solution and hydrochloric acid when they form sodium chloride solution and water.

Answer the questions about the compound sodium sulfate, Na2SO4.