CH3) Mass relations in chemistry

Question 1

Avogadro’s number and Mole

Answer 1

Na=6.022X10^23, if have Na of something then we say you have 1 “mole” of that thing

Answer 2

Number of atoms of an element in a sample whose mass in grams is numerically equal to the mass of single atom in atomic mass units

Question 3

Chemical formulas

Answer 3

Chapter 2 we learned the chemical formula

Question 4

Chemical analysis

Answer 4

• Experiment can give data that lead to the determination of the formula od a compound
• Massses of elements in the compounds
• mass percents of elements in the compound
• masses of products obained from the reactio of

Question 5

mASS RELATIONS IN CHEMICALS FORMULAS

Answer 5

• percent composition of a compound is stated as the number of grams of each element in 100g of the compound
• by knowing the formula the mass percent of each element can be readly calculated

Question 6

Emperical formula from chemical analysis

Answer 6

• often the formula is not known, but data from chemical analysis is known
• ammount of each element in grams
• can be used to determine the simplest formula
• smallest whole-number ratio of atoms in a compound
• H2O is the empirical formula and the molecular formula

Question 7

Molecular formula from simplest formula

Answer 7

• The relationship between simplest and molecular formula is a whole number
• the hwole number relates the molecular mass to the mass of the simplest formula as well

Question 8

Solute concentratrions-molarity

Answer 8

• molarity= moles of solute/liters of solution

Question 9

Additivity

Answer 9

Masses are additive; volumes are not
- total mass of a solution is the sum of the mass of the solute and the solvent
- total volume of a solution is not the sum of the volumes of the colute and solvent

Question 10

Volumetric glassware

Answer 10

• volumetric pipets, burets and flasks are made so that they. contain a known volume of liquid at a given temperatue
• preparing soltuions with concentrations in M involves using volumetric glassware

Question 11

Molarity as a conversion factor

Answer 11

• molarity can be used to calculate

Question 12

Disolving ionic solids

Answer 12

• ionic solid is dissolved in a solvent the ions separate from eachother
• MgCL2 (s) -> Mg2+ (aq) + 2 CL- (aq)
• concentrations of ions are related to eachother by the formula of the compound:
• molarity MgCl

Question 13

other concentration units

Answer 13

1) Mass percent
2) volume percent
3) parts per million, ppm/ppb