Speed and balance
Before you read
Test yourself first: 5 questions
Question 1 of 5
A substance that speeds up a chemical reaction without being consumed is a:
Answer: C. A catalyst lowers a reaction's activation energy and is regenerated, so it is not used up. In cells, enzymes act as biological catalysts.
Question 2 of 5
A substance that speeds up a reaction without being used up is a:
Answer: B. A catalyst lowers the activation energy and is not consumed by the reaction.
Question 3 of 5
In the reaction 2H₂ + O₂ → 2H₂O, the substances on the LEFT are called:
Answer: A. Reactants → products, always left to right. The arrow means 'becomes'.
Question 4 of 5
An exothermic reaction:
Answer: A. Exo- = exit (heat out, feels warm). Endo- = into (heat in, feels cold). A chemical cold pack is endothermic.
Question 5 of 5
In a chemical reaction, the starting substances are called the:
Answer: B. Reactants are the substances you start with; they combine to form products.
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