Every card in Chemical reactions, Year 8: more practice
The whole deck, in order — so you can read it through before your child ever sees it.
- There are 4 hydrogen atoms among the reactants in a reaction. How many hydrogen atoms must there be among the products? (number only)
4
HintAtoms are rearranged, never made or destroyed.
WhyThe same atoms are present before and after the reaction. They are just joined to different partners.
- 10.0 g of a carbonate is heated in an open tube and 5.6 g of solid is left. What mass of gas escaped? (number only, in grams)
4.4
HintNothing is lost: the missing mass left as a gas.
WhyMass is conserved, so the gas must account for the difference: 10.0 − 5.6 = 4.4 g.
- 12 g of magnesium reacts completely with 8 g of oxygen in a sealed container. What mass of magnesium oxide forms? (number only, in grams)
20
HintAdd the masses of the reactants.
WhyIn a closed system the total mass stays the same, so 12 + 8 = 20 g.
- Heating limestone (calcium carbonate) breaks it down into calcium oxide and which gas?
Carbon dioxide
HintCarbonates lose a gas when they are strongly heated.
WhyCalcium carbonate → calcium oxide + carbon dioxide. This is how quicklime is made.
- Why can an element such as copper not be broken down by thermal decomposition?
It is made of only one kind of atom, so there is nothing simpler to break into
HintThink about what decomposition has to produce.
WhyThermal decomposition splits a compound into simpler substances. An element contains only one kind of atom.
- Complete the word equation: copper + oxygen → ? (two words)
Copper oxide
HintThe metal gains the -ide ending to show oxygen has joined it.
WhyOxidation is the gain of oxygen. Copper turns black as copper oxide forms.
- Where does the heat given out by an exothermic reaction come from?
The energy stored in the reacting chemicals
HintThink about what a battery holds before it is used.
WhyReactants hold stored chemical energy. In an exothermic reaction some of it is released as heat.
- Put zinc, iron and sodium in order from most to least reactive.
Sodium, zinc, iron
HintThe soft metal that is kept under oil is the most reactive here.
WhyThe order in the series is sodium, then zinc, then iron. Most of the reactions are quicker the higher up the series a metal is.
- Gold is often found as a pure metal in the ground. What does this tell you about its reactivity?
It is very unreactive
HintMost metals are found joined to other elements in ores.
WhyUnreactive metals do not combine easily with oxygen or other elements, so they can survive uncombined for millions of years.
- Will zinc displace copper from copper sulfate solution? Give a reason.
Yes, because zinc is more reactive than copper
HintCheck which metal is higher in the reactivity series.
WhyA more reactive metal takes the place of a less reactive one in its compound: zinc + copper sulfate → zinc sulfate + copper.
1★ KS3-CHEM-REA-0045
2★ KS3-CHEM-REA-0046
3★ KS3-CHEM-REA-0047
4★ KS3-CHEM-REA-0048
5★ KS3-CHEM-REA-0049
6★ KS3-CHEM-REA-0050
7★ KS3-CHEM-REA-0051
8★ KS3-CHEM-REA-0052
9★ KS3-CHEM-REA-0053
10★ KS3-CHEM-REA-0054
Keep what you learn
Here, nothing is saved. In your child’s own sky every card is scheduled — it comes back just before they’d forget it — and the professor who wrote it is one tap away.