Amounts of substance in equations

Sodium hydroxide, NaOH, and calcium hydroxide, Ca(OH)₂, are ionic compounds that dissolve in water to form alkaline solutions.

Why are solutions of sodium hydroxide and calcium hydroxide called alkalis?

Explain why the formula of sodium hydroxide is NaOH but the formula of calcium hydroxide is Ca(OH)₂.

The electrolysis of a sodium hydroxide solution produces hydrogen at the cathode rather than sodium.

Explain why.

When carbon dioxide is bubbled through a calcium hydroxide solution it turns cloudy white.

This is the equation for the reaction.

Which chemical in the equation turns the solution cloudy white?

What is the alternative name for the calcium hydroxide solution?

The calcium hydroxide solution contains 0.038 g of calcium hydroxide.

Calculate the maximum mass of carbon dioxide that can react with the calcium hydroxide solution.

Give your answer to 2 significant figures.

Relative atomic mass (A_r): H = 1.0 C = 12.0 O = 16.0 Ca = 40.1

Copper can be made by reacting copper oxide, CuO, with carbon, C.

When 2.00 g of copper oxide reacts with 1.00 g of carbon, copper oxide is the limiting reactant.

Explain the effect of a limiting reactant on a reaction.

Calculate the number of moles in 2.00 g of copper oxide and 1.00 g of carbon.

Give your answers to 3 decimal places.

Relative atomic mass (A_r): C = 12.0 O = 16.0 Cu = 63.5

Use your answers in part (b) to explain why copper oxide is the limiting reactant.

The number of moles in a different mass of copper oxide is 0.045.

Calculate the maximum mass of copper, Cu, that can be made from 0.045 moles of copper oxide.

Give your answer to 2 significant figures.

Relative atomic mass (A_r): Cu = 63.5

A student completely reacts 0.403 g of magnesium oxide with an excess of carbon.

What is the mass of magnesium made?

The relative atomic mass, A_r, of O is 16.0 and of Mg is 24.3

A 0.1215 g

B 0.243 g

C 0.486 g

D 0.668 g

Copper can be extracted from copper sulfide by heating it in air.

Copper sulfide contains 74.0% copper by mass.

An ore contains 2.00% copper sulfide.

What is the maximum mass of copper that can be extracted from 150 kg of the ore?

A 1.48 kg

B 2.22 kg

C 3.00 kg

D 111 kg

Aluminium, phosphorus and magnesium are all in Period 3 of the Periodic Table.

Aluminium has an atomic number of 13 and mass number of 27.

Describe the nucleus of an aluminium atom in terms of sub-atomic particles.

What is the overall charge on the nucleus of an atom of aluminium?

Which sub-atomic particles surround the nucleus?

Phosphorus has a higher atomic number and a higher mass number than aluminium.

A student says that phosphorus must be an isotope of aluminium because it has a different number of neutrons.

Is the student correct?

Tick (✓) one box.

Explain your answer.

Phosphorus can react with oxygen to form oxides. One oxide of phosphorus is called phosphorus pentoxide.

Phosphorus pentoxide has the molecular formula P₄O₁₀.

What is the empirical formula of phosphorus pentoxide?

Aluminium oxide and phosphorus pentoxide have different types of bonding.

The boiling point of aluminium oxide is 2977 °C.

The boiling point of phosphorus pentoxide is 360 °C.

What conclusion can you make about the type of bonding in each oxide?

Explain your answers.

The student is given a sample of the metal magnesium and a solution of an unknown nitrate of metal M, MNO₃(aq).

The student does an experiment to identify metal M.

The student weighs the magnesium. Then the student adds the magnesium to the solution of the metal nitrate.

A displacement reaction takes place forming metal M:

The student separates the metal M and then weighs metal M.

Look at the student’s results: Mass of magnesium = 0.729 g Mass of metal M = 6.476 g

Calculate the moles of magnesium used in the experiment.

Calculate the relative atomic mass of metal M.

Give your answer to 3 significant figures.

Use your answer from (d)(ii) and the Periodic Table to identify the metal M.

Look at the equation for the equilibrium reaction between sulfur dioxide, SO₂, oxygen and sulfur trioxide, SO₃, in a closed system.

Predict the effect of adding more oxygen to the equilibrium mixture.

Explain your answer.

Predict the effect of increasing the total pressure in the equilibrium mixture.

Explain your answer.

Predict the effect of increasing the temperature of the equilibrium mixture.

Explain your answer.

Sulfur dioxide for this reaction is made by burning sulfur.

Calculate the mass of sulfur needed to make 48 tonnes of sulfur dioxide.

Give your answer to 2 significant figures.

The relative atomic mass, Ar, of S is 32.1 and of O is 16.0.

Answer =........ tonnes