Show:
level 1 & 2
molar mass of an element/compound
level 3 & 4
molar mass conversions
/avagadro's number conversions
level 5 & 6
molar volume conversions/ mole to gram conversions
level 7 & 8
percentage composition/ empirical formula problems
level 9
molecular formula problems
100
level 1- what is the molar mass of potassium?
39.098 grams
100
level 3- how many grams are in 3 moles of copper?
3 moles x 63.546 grams/mole= 190.638 grams
100
level 5- what volume will 1.00 mole of potassium occupy at STP?
1.00 mole x 22.4 liters/mole= 22.4 liters
100
level 7- what is the percentage composition by mass of NaHCO3?
mass % Na = 22.99 g / 84.01 g x 100 = 27.36 % mass % H = 1.01 g / 84.01 g x 100 = 1.20% mass % C = 12.01 g / 84.01 g x 100 = 14.30 % mass % O = 48.00 g / 84.01 g x 100 = 57.14 % Na= 27.36% H= 1.20% C= 14.30% O= 57.14%
100
level 9- if the empirical formula of a compound is H2O & its molecular mass is 54 grams/mole, what is its molecular formula?
H2O= 18 grams (54 grams/mole) / (18 grams/mole)= 3 H6O3
200
level 1- what element's molar mass is 196.97 grams?
gold
200
level 3- how many moles are in 196.17 grams of zinc?
196.17 grams/ 65.39 grams/mole= 3 moles
200
level 5- what volume will 3.5 moles of oxygen occupy at STP?
3.5 moles x 22.4 liters/mole= 78.4 liters
200
level 7- what is the percentage composition by mass of CO2?
mass % C = 12.01 g / 44.01 g x 100 = 27.29% mass % O = 32.00 g / 44.01 g x 100 = 72.71% C= 27.29% O= 72.71%
200
level 9- if the empirical formula of a compound is CH & its molecular mass is 78 grams/mole, what is its molecular formula?
H2O= 13 grams (78 grams/mole) / (13 grams/mole)= 6 C6H6
300
level 1- what is the molar mass of zinc?
65.39 grams
300
level 3- how many grams are in 2 moles of helium?
2 moles x 4.0026 grams/mole= 8.0052 grams
300
level 5- what volume will 2 moles of CO2 occupy at STP?
2 moles x 22.4 liters/mole= 44.8 liters
300
level 7- what is the percentage composition by mass of H2O?
mass % H = 2.0158 g / 18.0148 g x 100 = 11.19% mass % O = 15.999 g / 18.0148 g x 100 = 88.81% H= 11.19% O= 88.81%
300
level 9- if the empirical formula of a compound is CO2 & its molecular mass is 220 grams/mole, what is its molecular formula?
CO2= 44 grams (220 grams/mole) / (44 grams/mole)= 5 C5O10
400
level 2- what is the molar mass of nitrate?
nitrate= NO3 N= 14.007 grams O= 15.999 grams x 3 14.007 + 47.997= 62.004 grams
400
level 4- how many molecules are in 2 moles of barium?
2 moles x (6.02 x 10^23) molecules= 1.204 x 10^24 molecules
400
level 6- how many moles are in 25 grams of KCl?
molar mass of KCl= 74.551 grams 25 grams / 74.551 grams= 0.34 moles
400
level 8- what is the empirical formula for a compound that is 63% Mn & 37% O?
63 g Mn × (1 mol Mn)/(54.94 g Mn) = 1.1 mol Mn 37 g O × (1 mol O)/(16.00 g O) = 2.3 mol O 1.1 mol Mn/1.1 = 1 mol Mn 2.3 mol O/1.1 = 2.1 mol O Mn:O = 1:2 MnO2
400
level 9- if the empirical formula of a compound is NO2 & its molecular mass is 138 grams/mole, what is its molecular formula?
NO2= 46 grams (138 grams/mole) / (46 grams/mole)= 3 N3O6
500
level 2- what is the molar mass of water?
water= H2O H= 1.0079 grams x 2 O= 15.999 grams 2.0158 + 15.999 = 18.0148 grams
500
level 4- how many moles are in 2.408 x 10^24 atoms?
(2.408 x 10^24) atoms / (6.02 x 10^23) atoms/mole= 4 moles
500
level 6- how many moles are in 100. grams of NaCl?
molar mass of NaCl= 58.443 grams 100 grams / 58.443 grams= 1.71 moles
500
level 8- what is the empirical formula for a compound that is 50% carbon & 50% hydrogen?
50 g C × (1 mol C)/(12 g C) = 4.2 mol C 50 g H × (1 mol H)/(1 g H) = 50 mol H 4.2 mol C/4.2 = 1 mol C 50 mol H/4.2 = 12 mol H C:H = 1:12 CH12
500
level 9- if the empirical formula of a compound is MgO & its molecular mass is 80 grams/mole, what is its molecular formula?
MgO= 40 grams (80 grams/mole) / (40 grams/mole)= 2 Mg2O2