Physical Science- Chemical Reactions & Enzymes
Which of the following statements about enzymes is NOT true? 1. All enzymes work inside cells. 2. Enzymes work best at a specified pH. 3. Enzymes are proteins. 4. Enzymes are organic catalysts.
1. All enzymes work inside cells.
Which of the following statements is true about catalysts? 1. Catalysts lower the activation energy of a chemical reaction. 2. Catalysts are used up during a chemical reaction. 3. All catalysts are enzymes. 4. Catalysts slow down the rate of chemical reactions.
1. Catalysts lower the activation energy of a chemical reaction.
Which of the following will NOT increase the rate of a chemical reaction? 1. adding an inhibitor 2. increasing the surface area of a solid reactant 3. increasing the concentration of reactants 4. adding a catalyst
1. adding an inhibitor
In the following mathematical equation, what is the product? 12 x 6 x 4 = 288
288
Which of the following chemical reactions illustrates a single-displacement reaction? 4H2 + 2O2 > 2H2O 6CO2 + 6H2O + energy > C6H12O6 + 6O2 4KI + 2Cl2 > 4KCl + 2I2 2H2O > 2H2 + O2
4KI + 2Cl2 > 4KCl + 2I2
How many oxygen atoms are present in the reactant side of the chemical equation 4Fe + 3O2 > 2Fe2O3?
6
How can you be sure a chemical reaction is happening?
A new substance is formed.
What is needed to get a reaction started?
Activation Energy
Identify the reactant(s) in the chemical reaction, CO2 + H2O > H2CO3.
CO2 and H2O
Which of the following chemical equations is balanced? Ca + O2 > CaO2 3Ca + 2O2 > 5CaO2 3Ca + O2 > 3CaO2 Ca + 2O2 > 2CaO2
Ca + O2 > CaO2
How do enzymes relate to catalysts?
Enzymes are catalysts produced by living things
________ work by creating an ideal environment for the reaction to take place. (1. Proximity 2. Orientation) This ________ the energy needed for the reaction to take place.
Enzymes; reduces
What do catalysts do to a reaction?
Increase speed of the reaction
What is the product in the chemical formula N + O2 > NO2?
NO2
How do enzymes change a reaction?
They lower the activation energy.
True or false: Enzymes are proteins.
True
Paper (cellulose) burns in the presence of oxygen and releases heat and light. Why then aren't your books all on fire?
You need a spark to get the reaction started.
Chemical reactions that ______ energy will not occur without a source of energy.
absorb
If a reaction in one direction releases energy, the reaction in the opposite direction...
absorbs energy.
Like other catalysts, enzymes do this by lowering the __________ ______ of a reaction.
activation energy
The energy needed to get a chemical reaction started is __________ ______.
activation energy
What is the term used to describe the energy needed to get a reaction started?
activation energy
Substrates bind to a specific location on the enzyme known as the ______ ____. This association is called the ______-_________ _______.
active site; enzyme; substrate complex
A substance that accelerates the rate of a chemical reaction is called a(an) ________.
catalyst
A substance that speeds up the reaction rate but is not consumed in the reaction is a _________.
catalyst
Changes in pH or temperature can cause changes in an enzyme's shape that can reduce (or destroy) its effectiveness as a ________.
catalyst
Enzymes are __________.
catalysts
Enzymes are organic _________.
catalysts
Chemical reactions always involve changes in the _________ ______ that join atoms in compounds.
chemical bonds
A ________ _________ is a process that changes (or transforms) one set of chemicals into another.
chemical reaction
A ________ _________ is a process that changes or transforms one set of chemicals into another.
chemical reaction
What is the process that changes one set of chemicals into another set of chemicals?
chemical reaction
Chemical equations must be balanced to satisfy the law of ____________ __ _____.
conservation of mass
What kind of reaction absorbs energy from the surrounding area?
endothermic
If the reactants (the starting conditions) have less energy than the products (the ending conditions), then energy is absorbed (also known as an ___________ _________).
endothermic reaction
True or false: Chemical reactions only occur in one direction, producing energy.
false
True or false: Chemical reactions that release energy require a catalyst in order for the reaction to occur.
false
True or false: The substances that are present when a chemical reaction begins are the products.
false
The fit between substrate and active site is so precise that it is frequently compared to a "____ and ___".
lock; key
A catalyst speeds up the rate of a chemical reaction by...
lowering a reaction's activation energy.
Enzymes speed up chemical reactions that take place in cells by (like other catalysts)...
lowering the activation energy of a reaction.
In a single-displacement reaction, a ____ reactive element can replace a ____ reactive element.
more; less
If the reactants (the starting conditions) have _____ energy than the products (the ending conditions), then energy is _________ (also known as an exothermic reaction).
more; released
Chicken...
nuggets
Enzymes work best at a specified __.
pH
In reversible reactions, one direction will ________ energy, and the other direction will _______ energy.
produce; require
The elements or compounds produced by a chemical reaction are known as ____________________.
products
Enzymes are ________ that act as biological catalysts.
proteins
Chemical reactions that ______ energy often occur spontaneously.
release
Depending on the number and types of chemical bonds broken and formed, energy may be either ________ or _________ by chemical reactions.
released; absorbed
An example of activation energy is when paper (cellulose) burns in the presence of oxygen and _________ heat and light.
releases
It is the _____ of the large enzyme molecules that allow them to function.
shape
It is the _____ of these large enzyme molecules that allows them to function.
shape
Enzymes ______ __ chemical reactions that take place in cells.
speed up
When you increase the temp of a chemical reaction, the reaction _______ ___.
speeds up
The reactants of enzyme-catalyzed reactions are known as ___________.
substrates
Without enzymes, the thousands of chemical reactions necessary to sustain life would simply be ___ ____.
too slow
