When iron combines with oxygen and water in the air to form rust, what substance in the reaction is the product?
__________ tells you how much something changes during a period of time.
|A)||A balanced chemical equation|
A change in which one or more substances are converted into new substances is a __________ .
The amount of substance present in a certain volume is called the __________ of that substance.
What type of substance slows down a chemical reaction?
A(n) __________ is a substance that speeds up a chemical reaction without being permanently changed itself.
New substances produced by a chemical reaction are __________ .
In chemical equations, __________ represent the number of units of each substance.
|C)||numbers in front of the chemical formulas|
Which of the following statements about energy-releasing reactions is true?
|A)||The bonds of the products have more energy than those of the reactants.|
|B)||The energy released is always in the form of heat.|
|C)||The products are more stable.|
|D)||The products are less stable.|
Most chemical reactions __________ when temperature increases.
|B)||continue at the same rate|
The law of conservation of mass states that __________ .
|A)||matter can be created and destroyed but does not change forms|
|B)||in a chemical reaction, matter is not created or destroyed, but is conserved|
|C)||in a chemical reaction, the final mass of the products is always greater than the starting mass of the reactants|
|D)||in a chemical reaction, efforts should be made to preserve rare elements without changing them|
The chemical formula for a compound tells __________ .
|A)||what type of chemical bond it forms|
|B)||how stable the compound is|
|C)||how electrons are arranged|
|D)||what elements it contains|
In a chemical equation for an endothermic reaction, how is the energy requirement indicated?
|A)||The word energy is written as a reactant.|
|B)||A Greek letter, gamma, is drawn over the arrow.|
|C)||The word energy is written as a product.|
|D)||A letter E appears in boldface type over the arrow.|
As a result of the experiments of Lavoisier, you know that in a chemical reaction, the mass of the products __________.
|A)||is less than the mass of the reactants|
|B)||always equals the mass of the reactants|
|C)||cannot be predicted based on the mass of the reactants|
|D)||is twice as great as the mass of the reactants|
__________ is a way to describe a chemical reaction using chemical formulas and symbols.
|A)||A physical law|
|C)||The law of conservation of matter|
|D)||A chemical equation|
The minimum amount of energy to start any chemical reaction is called the __________ of the reaction.
|B)||energy of catalyzation|
|C)||energy of inhibition|
If electric current passes through water and initiates a reaction, what are the expected products?
|A)||hydrogen and oxygen|
|D)||oxygen and water|
__________ reactions absorb heat energy.
__________ reactions release heat energy.
Which of the following statements about energy-absorbing reactions is true?
|A)||The bonds of the reactants have more energy than those of the products.|
|B)||The energy supplied is always in the form of electricity.|
|C)||The reactants are less stable.|
|D)||The reactants are more stable.|