A change in which one or more substances are converted into new substances is a __________ .
New substances produced by a chemical reaction are __________ .
__________ is a way to describe a chemical reaction using chemical formulas and symbols.
|B)||A physical law|
|C)||The law of conservation of matter|
|D)||A chemical equation|
As a result of the experiments of Lavoisier, you know that in a chemical reaction, the mass of the products __________.
|A)||is twice as great as the mass of the reactants|
|B)||always equals 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 stable the compound is|
|B)||what type of chemical bond it forms|
|C)||what elements it contains|
|D)||how electrons are arranged|
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, efforts should be made to preserve rare elements without changing them|
|C)||in a chemical reaction, matter is not created or destroyed, but is conserved|
|D)||in a chemical reaction, the final mass of the products is always greater than the starting mass of the reactants|
In chemical equations, __________ represent the number of units of each substance.
|A)||numbers in front of the chemical formulas|
Which reactant correctly balances the following equation: 4Al + __________ → 2Al2O3?
What is the correct number to write in front of mercury(II) oxide (HgO) in the following equation: HgO → 2Hg + O2?
Which of the following symbols in a chemical equation means "produces"?
Why is oxygen written with a subscript 2 in CO2?
|A)||Its mass is twice as great as the reactants'.|
|B)||Carbon always bonds to two oxygen atoms.|
|C)||Each molecule of carbon dioxide has two oxygen atoms.|
|D)||Its mass increases by two times as a result of the reaction.|
What does it mean for a chemical equation to be balanced?
|A)||The solid products weigh the same as the reactants.|
|B)||The reactants and the products are written with the same coefficients.|
|C)||There are the same number of atoms of each element on both sides of the equation.|
|D)||The number of reactants is equal to the number of products.|
A(n) __________ is a substance that speeds up a chemical reaction without being permanently changed itself.
Which of the following statements about energy-releasing reactions is true?
|A)||The products are more stable.|
|B)||The products are less stable.|
|C)||The bonds of the products have more energy than those of the reactants.|
|D)||The energy released is always in the form of heat.|
Which of the following statements about energy-absorbing reactions is true?
|A)||The reactants are less 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 more stable.|
__________ reactions release heat energy.
__________ reactions absorb heat energy.
In a chemical equation for an endothermic reaction, how is the energy requirement indicated?
|A)||The word energy is written as a product.|
|B)||The word energy is written as a reactant.|
|C)||A letter E appears in boldface type over the arrow.|
|D)||A Greek letter, gamma, is drawn over the arrow.|