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