Reactions

Question 1

State 3 signs of a chemical reaction

Answer 1

Change in colour, change in temperature, bubbles or gas being given off

Additional signs may include light production and formation of a new product.

Question 2

Describe what is meant by the conservation of mass

Answer 2

The mass of the reactants will be equal to the mass of the products of the reaction

This principle states that matter is neither created nor destroyed in a chemical reaction.

Question 3

A substance is changing from being a gas to being a liquid. State whether this is a physical change or a chemical reaction.

Answer 3

It’s a physical change as the composition of the substance doesn’t change

This process is known as condensation.

Question 4

What is a displacement reaction?

Answer 4

An element that is more reactive replaces another less reactive element in a compound

This reaction typically involves a metal displacing another metal from its compound.

Question 5

Complete the general word equation for the reaction between a metal and an acid.

Answer 5

metal + acid → metal salt + hydrogen

This equation summarizes the reaction between a metal and an acid producing a salt and hydrogen gas.

Question 6

Name the salts produced using hydrochloric acid, sulfuric acid, and nitric acid.

Answer 6

Metal chloride, metal sulfate, metal nitrate

These salts correspond to the respective acids when they react with metals.