Compounds and Stoichiometry .

Question 1

What are compounds?

Answer 1

They are substances composed of two or more elements in a fixed proportion.

Question 2

What is molecular weight?

Answer 2

It is the mass (in amu) of the constituent atoms in a compound as indicated by the molecular formula.

Question 3

what is molar mass?

Answer 3

It is the mass of one mole (avagadro’s) of a compound; usually measured in grams per mole.

Question 4

Gram equivalent weight

Answer 4

a measure of the mass of a substance that can donate one equivalent of the species of interest.

Question 5

Normality

Answer 5

The ratio of equivalents per liter; it is related to molarity by multiplying the molarity by the number of equivalents present per mole of a compound.

Question 6

Equivalents

Answer 6

are moles of the species of interest; are most often in acid-base chemistry (hydrogen ions or hydroxide ions) and oxidation-reduction reactions (moles of electrons or other ions)

Question 7

What is the law of composition?

Answer 7

states that any pure sample of a compound will contain the same elements in the same mass ratio.

Question 8

What is empirical formula?

Answer 8

the smallest whole-number ratio of the elements in a compound.

Question 9

What is the molecular formula?

Answer 9

it either the same as or a multiple of the empirical formula; it gives the exact number of atoms

Question 10

What is the percent composition?

Answer 10

by mass, determines the mass of the individual element and divide by the molar mass of the compound.

Question 11

What are combination reactions?

Answer 11

Occur when two or more reactants combine to from one product.

Question 12

What are decomposition reactions?

Answer 12

occur when one reactant is chemically broken down in two or more products.

Question 13

What is displacement reactions?

Answer 13

Occurs one or more atoms or ions of one compound are replaced with one or more atoms of ions of anther compound.

Question 14

Single displacement reactions

Answer 14

occurs when an ion of one compound is replaced with another element.

Question 15

Combustion reactions?

Answer 15

occur when a fuel and an oxidant (typically oxygen) react, forming the products and water and carbon dioxide.

Question 16

double displacement reactions

Answer 16

When elements form two different compounds swap places with each other to form two new compounds. Also known as metathesis reaction.

Question 17

neutralization reactions

Answer 17

are those in which an acid react with a base to form a salt (and usually water)

Question 18

Balanced equation are determined by using…?

Answer 18

balance the least common atom
balance the more common atoms (usually hydrogen and oxygen.
Balancing the charge, if necessary.

Question 19

What is the limiting reagent

Answer 19

the reactant that will be consumed first in a chemical reaction.

Question 20

What is the excess reagent?

Answer 20

the other reactants that are not the limiting.

Question 21

What is theoretical yield?

Answer 21

The amount of product generated fi all of the limiting reactant is consumed with no side reactions.

Question 22

What is the actual yield?

Answer 22

typically lower than the theoretical and what actually occurs

Question 23

What is percent yield?

Answer 23

Calculated by dividing actual yield by theoretical yield and converting into a percentage.

Question 24

Roman numeral are used in ions to…

Answer 24

represent charge in elements

Question 25

-ous ending indicates what in elements

Answer 25

a lesser charge

Question 26

-ic ending indicates

Answer 26

a greater charge .

Question 27

all monatomic anions end in

Answer 27

-ide

Question 28

Oxyanions that contains -ite suffix are…

Answer 28

lesser amount of oxygen

Question 29

Oxyanions that contain -ate suffix are…

Answer 29

greater amount of oxygen

Question 30

Oxyanion series with more than two members are given an additional nomenclature that is..

Answer 30

the fewest oxy hypo-, more oxy per-

Question 31

Hydrogens are denoted in polyatomic compounds by..

Answer 31

hydrogen, or bihydrogen.

Question 32

How are ion charges predicted?

Answer 32

by group number and type of element fro representative elements, but are generally unpredictable for nonrepresentative elements. Metals form positively charge cations based on group numbers. Nonmetals form negatively charge anions based on the number of electrons needed to achieve octet.

Question 33

Electrolytes

Answer 33

contain equivalents of ions from molecules that dissociate in solution. The strength of and electrolyte depends on its degree of dissociation or solvation.

Question 34

Mole from mass equation

Answer 34

Mass of sample/molar mass

Question 35

Gram equivalent weight

Answer 35

GEW= molar mass/n

Question 36

Equivalents from mass

Answer 36

equivalents = mass of compound/gram equivalent weight

Question 37

Molarity from normality

Answer 37

molarity=normality/n

Question 38

percent composition

Answer 38

% composition =mass of element in formula/molar mass . x 100%

Question 39

percent yield

Answer 39

%yield = actual yield / theoretical yield x 100% .

Question 40

NH4+

Answer 40

ammonium

Question 41

C2H3O2-

Answer 41

acetate

Question 42

CN-

Answer 42

Cyanide

Question 43

MnO4-

Answer 43

permanganate

Question 44

SCN-

Answer 44

Thiocyanate

Question 45

CrO4 2-

Answer 45

chromate

Question 46

Cr2O7 2-

Answer 46

dichromate

Question 47

BO3 3-

Answer 47

Borate