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Terms in this set (37)
1 activation energy
activation energy is the minimum amount of energy needed to start a chemical reaction. All chemical reactions need a certain amount of activation energy to get started.
Concentration is the amount of a substance in a given volume.
A catalyst (kat uh list) is a material that increases the rate of a reaction by lowering the activation energy.
4 Do catalysts affect a reaction's rate?
5 Are catalyst permanently changed by a reaction?
6 Is a catalyst a reactant?
7 Is an enzyme a kind of catalyst?
An enzyme is a biological catalyst that affects only one chemical rection
A material used to decrease the rate of a reaction is an inhibitor.
10 How do inhibitors work?
Most inhibitors work by preventing reactants from coming together. Usually they combine with one of the reactants either permanently or temporarily.
11 How are inhibitors used in food production?
Inhibitors include preservatives added to food products to prevent them from becoming stale or spoiling.
12 How do we control rates of reactions?
By changing factors such as
1. surface area,
4. adding catalysts and inhibitors.
13 What do all chemical reactions need to get started?
a certain amount of activation energy
14 T/F Overall, the reaction releases more energy than it uses.
15 At the end of the exothermic reaction, the products have less or more energy than the reactants?
16 Give some examples of exothermic reactions
The burning of fuel, such as wood, natural gas, or oil, is an example of an exothermic reaction. People can make use of the heat that is released to warm their homes and cook food.
17 T/F Endothermic reactions need activation energy to get started and they need energy to keep going..
18 Is the energy of the products higher or lower than that of the reactants in endothermic reactions? .
19 The minimum amount of energy required to start a chemical reaction is the Hint
A. exothermic energy.
B. activation energy.
C. endothermic energy.
D. reactant energy.
B. activation energy.
20 A material that increases the rate of a chemical reaction by lowering the activation energy is called a(n) Hint
21 A substance that reduces the rate of a chemical reaction is called a(n) Hint
22 Which would react more quickly in a chemical reaction: a single sugar cube or an equal mass of sugar crystals? Explain.
sugar crystals because they have more surface area and will react more quickly
23 The ---------------- is the minimum amount of energy needed to start a chemical reaction
24 T/F All chemical reactions need a certain amount of activation energy to get started
25 a reaction that releases energy
26 a reaction that absorbs energy
27 why does an exothermic reaction need activation energy?
ALL chemical reactions need activation energy to get started! But exothermic reactions will release energy so they end up with less energy than they started with.
28 Why does the surface area of a reactant influence the rate of a reaction?
Surface area influences the rate of a reaction because the greater the surface area the more particles available to react and the reaction speeds up.
29 How is temperature related to chemical reaction rates?
higher temperatures speed up reactions
lower temperatures slow down reactions
30 the amount of substance in a given volume is called _______
31 How does increasing the concentration increase the rate of reactants?
Increasing concentration increases the amount of available reactants so if there are more reactants available to react with each other the reaction happens faster. Colliding =reacting and the more available particles =more collisions.
32 T/F you can control the rate of a reaction by changing the amount of activation needed.
True. A catalyst is an example of this since it speeds up chemical reactions by lowering the activation energy!
33 T/F Catalysts are always permanently changed in a reaction.
False. Catalysts are not changed during chemical reactions. So they are not products or reactants (and sometimes are shown above the arrow of the chemical reaction).
34 HOw do most inhibitors work?
Inhibitors usually work by preventing reactants from coming together.
The ability to do work and cause a change to occur
36 surface area
the amount of area that is exposed to reacants
37 When a substance is finely divided it has a large surface area for molecules to interact with, increasing or decreasing the rate of reaction
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