Chemists use symbols and formulae to represent elements, ions and compounds. Chemical equations model the changes that happen in chemical reactions.
What is the correct formula for carbon dioxide?
Water is produced when hydrogen reacts with oxygen. Which of these shows a balanced equation for this reaction?
2H2 + O2 → 2H2O
2H2 + O2 → H2O
H2 + 2O2 → 2H2O
What is the state symbol for a solid?
What is the empirical formula of C4H8O2?
3.0 g of carbon reacts with excess oxygen to form 11.0 g of carbon dioxide. What mass of oxygen reacted?
You cannot say from the information given
What is the relative formula mass of calcium carbonate, CaCO3? (Relative atomic masses: Ca = 40.1, C = 12.0, O = 16.0)
Iron(III) oxide contains Fe3+ ions and O2- ions. What is its formula?
Sodium nitrate contains Na+ ions and NO3- ions. What is its formula?
Which of these is a balanced ionic equation? - Higher
Pb2+ + Cl- → PbCl
Pb2+ + 2Cl- → PbCl2
Pb+ + 2Cl- → PbCl2
Which of these is a balanced half equation? - Higher
4OH- → 2H2O + O2 + 4e-
4OH- → H2O + O2 + 4e-
4OH- → 2H2O + O2 + e-