Chemists use symbols and formulae to represent elements, ions and compounds. Word equations and balanced chemical equations model the changes that happen in chemical reactions.
Which element has a formula that shows its molecules contain two atoms joined together?
What is the correct formula for ammonia?
Which of the following compounds is made up of molecules that contain five atoms?
Which of these compounds is most likely to contain ions?
What is the correct formula for sodium oxide, which is formed by joining positive sodium ions (Na+) to doubly negative oxide ions (O2-)?
What is the word equation for a reaction where hydrogen and carbon monoxide are the products, and water and carbon are the reactants?
hydrogen + carbon monoxide → water + carbon
water + carbon → hydrogen + carbon monoxide
carbon + carbon monoxide → hydrogen + water
Which equation shows a substance dissolved in water reacting to form a gas?
Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)
C(s) + H2O(g) → CO(g) + H2(g)
HCl(g)+ NaOH(aq) → NaCl(aq) H2O(l)
In this unbalanced symbol equation: Na + Cl2 → NaCl what is the correct balanced equation?
2Na + Cl2 → NaCl
2Na + Cl2 → 2NaCl
Na + Cl2 → 2NaCl
Which equation is balanced correctly?
SO2 + O2 → SO3
SO2 + 2O2 → 2SO3
2SO2 + O2 → 2SO3
Which ions can be missed out when writing this ionic equation?
AgNO3(aq) + KBr(aq) → AgBr(s) + KNO3(aq)
Silver (Ag+) ions and nitrate (NO3-) ions
Potassium (K+) ions and nitrate (NO3-) ions
Potassium (K+) ions and silver (Ag+) ions