EasyChemistryHigh School (9–10)GeneralChemical Reactions › Chemical EquationsChemical Reactions › Types of Chemical ReactionsConceptualBoard Exam
Name the sign of a chemical reaction that you see in each case…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Name the sign of a chemical reaction that you see in each case.
- Zinc is put in dilute acid, and bubbles come out.
- Green copper carbonate powder turns black when it is heated.
- Two clear solutions are mixed, and a white solid appears.
- Quicklime is added to water, and the glass becomes hot.
Need a reminder? The key ideaShow
In a chemical change, new substances form. Signs: a gas is given off, the colour changes, a precipitate forms, the temperature changes, or the state changes. A physical change, such as melting or dissolving, makes no new substance.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) A gas is given off.
Step 2. (b) A change of colour: a new black substance, copper oxide, forms.
Step 3. (c) A precipitate forms.
Step 4. (d) A change of temperature: heat is given out.
Answer: gas; colour change; precipitate; temperature change.
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