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