quantitative chemistry

Question 1

conservation of mass

Answer 1

sum of mass of reactants = sum of mass of products

Question 2

amu

Answer 2

atomic mass unit

Question 3

2 elements combine

Answer 3

-ide

Question 4

more than 2 elements combine

Answer 4

-ate

Question 5

2 or more atoms of same element

Answer 5

no change

Question 6

what does iron (II) mean

Answer 6

indicates charge on transition metal. fe 2+

Question 7

ionic compounds and charge

Answer 7

no overall charge - total positive charge = total negative charge

Question 8

hydroxide

Answer 8

OH-

Question 9

carbonate

Answer 9

CO3 2-

Question 10

zinc

Answer 10

Zn 2+

Question 11

nitrate

Answer 11

NO3 -

Question 12

ammonium

Answer 12

NH4 +

Question 13

lead

Answer 13

Pb 2+

Question 14

sulfate

Answer 14

SO4 2-

Question 15

copper

Answer 15

Cu 2+

Question 16

silver

Answer 16

Ag+

Question 17

relative atomic mass

Answer 17

mean average mass of an atom of an element expressed in AMU

Question 18

how to calculate relative atomic mass with percentage abundance

Answer 18

(M1 * 0.P1) * (M2 * 0.P2) = RMA

Question 19

relative formula mass

Answer 19

sum of all atomic masses present in the formula (Mr)

Question 20

relative molecular mass

Answer 20

sum of all atomic masses present in the formula (Mr)

Question 21

percentage by mass

Answer 21

RFM of wanted element / RFM

Question 22

why are moles used?

Answer 22

different chemicals contain different atoms -> mass cannot be used to compare particles easily

Question 23

what is avagadro’s constant

Answer 23

6.02 * 10^23

Question 24

what is the equation for moles

Answer 24

n = number of particles (mol)
Mr = relative formula/molecular mass
m = mass in g

n * Mr = m

Question 25

how were equations made before the periodic table?

Answer 25

• evidence for a formula had to be worked out using practical methods
• ratio between reactants and products could be found by experiment
• dalton’s atomic weights meant chemists could calculate ratios of particles
• moles = numbers of particles (for us)

Question 26

what is an excess of a chemical

Answer 26

having more of a chemical than required for a reaction

Question 27

which is the limiting reactant

Answer 27

the chemical that is completely used up first

Question 28

do you use the mass of the reactant in excess

Answer 28

no - only the mass of the limiting reactant

Question 29

how is the limiting reactant calculated

Answer 29

you have 2.4g of Mg and 2.0g of O2
2mg + 02 -> 2MgO

1) 1 O2 + 2 Mg -> 1 MgO
0.0625 * 2 = 0.125 moles of mg

0.1 moles of Mg and up to 0.125 of O2 present, excess of O2 and Mg is limiting

Question 30

solution

Answer 30

mixture of a solute and solvent

Question 31

solute

Answer 31

a soluble solid that dissolves in a solvent

Question 32

saturated solvent

Answer 32

no more solute can dissolve in the solvent

Question 33

what is concentration

Answer 33

quantity of solute / quantity of liquid

Question 34

what is the measurement of concentration?

Answer 34

1) grams per cubic decimeter
g/dm^3

2) mol per cubic decimeter
mol/dm^3

Question 35

how do you convert from cubic centimeters to cubic decimeters

Answer 35

divide by 1000

Question 36

how do you convert from cubic decimeters to cubic centimeters

Answer 36

multiply by 1000