1. Convert each of the following into scientific notation.
a) 3427 / b) 0.00456 / c) 123,453d) 172 / e) 0.000984 / f) 0.502
g) 3100.0 x 102 / h) 0.0114 x 104 / i) 107.2
j) 0.0000455 / k) 2205.2 / l) 30.0 x 10-2
m) 0.982 x 10-3 / n) 0.0473 / o) 650.502
2. Determine the number of significant figures in each of the following:
a) 3427 / b) 0.00456 / c) 123,453d) 172 / e) 0.000984 / f) 0.502
g) 3100.0 x 102 / h) 0.0114 x 104 / i) 107.2
j) 0.0000455 / k) 2205.2 / l) 30.0 x 10-2
m) 0.982 x 10-3 / n) 0.0473 / o) 650.502
3. Convert each into decimal form.
1.56 x 104 / 0.56 x 10-2 / 3.69 x 10-2 / 736.9 x 1050.00259 x 105 / 0.000459 x 10-1 / 13.69 x 10-2 / 6.9 x 104
0.00259 x 103 / 0.0209 x 10-3
4. Calculate the following. Give the answer in correct scientific notation.
a) 4.53 x 105 b) 1913.0
+ 2.2 x 106 - 4.6 x 103
c) 2.34 x 1024 d) 2.130 x 103
+ 1.92 x 1023 - 6.6 x 102
e) 6.18 x 10-45 f) 4.25 x 10-3
+ 4.72 x 10-44 - 1.6 x 10-2
5. Calculate the following. Give the answer in correct scientific notation.
a) 3.95 x 102/1.5 x 106 b) (3.5 x 102)(6.45 x 1010)
c) 4.44 x 107 /2.25 x 105 d) (4.50 x 10-12)(3.67 x 10-12)
e) 6.022 x 1023 / 3.011 x 10-56 f) (6.88 x 102)(3.45 x 10-10)
Isotopes Worksheet
1. Determine the number of protons, neutrons, and electrons for the following
a. 28Sip_____n_____e_____
b. 131Xep_____n_____e_____
c. 207Pb+2p_____n_____e_____
d. 127I-1p_____n_____e_____
2. Silver exists as 51.84% 107Ag and 48.16% 109Ag. The actual mass of 107Ag is 106.90509 amu and the actual mass of 109Ag is 108.90476. What is the average atomic mass of silver?
3. The average atomic mass of copper is 63.55 amu. If the only two isotopes of copper have masses of 62.94 amu and 64.93 amu, what are the percentages of each?
4. Boron has only two isotopes, 10B with a mass of 10.0129 and 11B with a mass of 11.0093. If the average atomic mass of boron is 10.81, what are the percentages of each isotope?
BALANCING EQUATIONS BY INSPECTION
- 1.Al + Fe3O4Al2O3 + Fe
3. CH3OH + O2CO2 + H2O
4.P4O10 + H2OH3PO4
5.PCl5 + H2OH3PO4 + HCl
6.SbCl5 + H2OSbOCl3 + HCl
7.MgO + SiMg + SiO2
8.CaCl2 + Na2CO3CaCo3 + NaCl
9.C6H6 + O2CO2 + H2O
10. Al2S3 + H2OAl(OH)3 + H2S
11.C2H6 + O2CO2 + H2O
12.KClO3KCl + KClO4
13.KBr + ClKCl + Br2
14.(NH4)2SO4 + NaOHNH3 + H2O + Na2SO4
15. Calcium Phosphate reacts with Sulfuric Acid to give Phosphic acid and Calcium Sulfate as a solid. Write the balanced equation for this reaction.
Moles Worksheet
Directions: For the following problems, show a complete set-up, cancellation of like units, and the answer with proper significant figures.
1) What is a mole?2) How many atoms are in one mole of an element?
3) 25.5 g of carbon to atoms4) 41.3 g of carbon to moles
5) 1.94 moles of copper to grams6) 4.28 moles of magnesium to grams
7) 6.70 moles of magnesium to atoms8) 0.636 moles of sulfur to grams
9) 1.98 moles of sulfur to atoms10) 2.19 moles of water (H2O) to grams
11) 1.59 moles of water to molecules12) 7.78 X 1023 atoms of Ca to grams
13) 8.90 X 1023 atoms of Ca to moles14) 7.67 X 1023 atoms of Mg to grams
15) 11.5 moles of Na to grams16) 9.93 moles of Na to atoms
17) 956 grams of NaOH to moles18) 829 grams of NaOH to molecules
19) 55.5 moles of water to grams20) 7.28 moles of water to molecules
This page is designed to help students practice written problems, and is meant to be printed out. Hit the print command and show all work in the spaces provided. Use the 5-step method, and be sure to round you answers correctly.(Observed Value - True Value)
Percent Error = ------x 100
True Value
1. Working in the laboratory, a student find the density of a piece of pure aluminum to be 2.85 g/cm3. The accepted value for the density of aluminum is 2.699 g/cm3. What is the student's percent error?
2. A student experimentally determines the specific heat of water to be 4.29 J/g x Co. He then looks up the specific heat of water on a reference table and finds that is is 4.18 J/g x Co. Whatis his percent error?
3. A student takes an object with an accepted mass of 200.00 grams and masses it on his own balance. He records the mass of the object as 196.5 g. What is his percent error?
Answers 1) 5.59% 2) 2.63% 3) -1.75%
Balance the following chemical equations.
1.
_____C2H6(g) + _____O2(g) ---> _____H2O(g) + _____CO2(g)
2.
_____O2 + _____C6H12O6 ---> _____H2O + _____CO2
3.
___Br2(g) + ___H2O(l) + ___SO2(g) ---> ___HBr(aq) + ___H2SO4(aq)
4.
_____KOH + _____H3PO4 ---> _____K3PO4 + _____H2O
5.
_____Mg + _____N2 ---> _____Mg3N2
6.
_____KNO3(s) ---> _____KNO2(s) + _____O2(g)
7.
_____Fe + _____H2SO4 ---> _____Fe2(SO4)3 + _____H2
8.
_____MgCO3(s) ---> _____MgO(s) + _____CO2(g)
Change the following masses to moles, by dividing the mass by the molar mass.
# of Moles = mass given/molar mass
1. How many moles does 80.0 grams of H2O represent? / 2. How many moles does 45.0 grams of C6H12O6
represent?
3. How many moles does 22.0 grams of CO2 represent? / 4. How many moles does 56.0 grams of N2 represent?
Change the following number of moles to mass by multiplying the number of moles by the molar mass.
mass of sample = # of moles x molar mass
1. What is the mass of 2.0 moles of LiOH ? / 2. What is the mass of 5.0 moles of Ba(CN)2 ?
3. What is the mass of 3.5 moles of water? / 4. What is the mass of 0.75 moles of CuSO4 ?
Change the following number of moles to number of particles by multiplying by Avogadro's number.
# of particles = # of moles x (6.02 x 1023)
1. How many atoms does 2.0 moles of He represent? / 2. How many sodium ions are in 3.0 moles of NaCl?
3. How many molecules are in 0.25 moles of CH4? / * 4. How many total atoms are in 1.0 moles of H2O ?
Change the following number of particles to number of moles by dividing by Avogadro's number.
# of moles = # of particles / (6.02 x 1023)
1. How many moles of water does 6.02 x 1023 molecules represent? / 2. Convert 3.01 x 1023 molecules of C2H6 to moles.
3.How many moles of glucose does 1.2 x 1024 molecules represent? / 4. How many moles of CaCl2 does 2.41 x 1024 formula units represent?
Change the following number of particles to masses by:
A) dividing by the number of particles by Avogadro's number to get number of moles, and then
B) multiplying number of moles by the molar mass
1. What would be the mass of 1.20 x 1024 molecules of water? / 2. What would be the mass of 2.41 x 1024 formula units of barium hydroxide?
3.How much mass does 1.51 x 1022 atoms of neon represent? / 4. How much mass does 7.53 x 1022 molecules of CH4 represent?
Change the following masses to number of particles by:
A) dividing by the molar mass to get the number of moles, and then
B) multiplying number of moles by Avogadro's number
1. How many molecules does 36.0 grams of water represent? / 2. How many molecules does 11.0 grams of CO2 represent?
3.How many atoms does 3.0 grams of carbon represent? / * 4. How many formula units does 200.0 grams of calcium carbonate represent?
Limiting Reagents and Percentage Yield Worksheet
1. / Consider the reaction
I2O5(g) + 5 CO(g) ------> 5 CO2(g) + I2(g)
a) 80.0 grams of iodine(V) oxide, I2O5, reacts with 28.0 grams of carbon monoxide, CO.
Determine the mass of iodine I2, which could be produced?
b) If, in the above situation, only 0.160 moles, of iodine, I2 was produced.
i) what mass of iodine was produced?
ii) what percentage yield of iodine was produced.
2. / Zinc and sulphur react to form zinc sulphide according to the equation.
Zn + S ------> ZnS
If 25.0 g of zinc and 30.0 g of sulphur are mixed,
a) Which chemical is the limiting reactant?
b) How many grams of ZnS will be formed?
c) How many grams of the excess reactant will remain after the reaction is over?
3. / Which element is in excess when 3.00 grams of Mg is ignited in 2.20 grams of pure oxygen?
What mass is in excess? What mass of MgO is formed?
4. / How many grams of Al2S3 are formed when 5.00 grams of Al is heated with 10.0 grams S?
5. / When MoO3 and Zn are heated together they react
3 Zn(s) + 2 MoO3(s) ------> Mo2O3(s) + 3 ZnO(s)
What mass of ZnO is formed when 20.0 grams of MoO3 is reacted with 10.0 grams of Zn?
6. / Silver nitrate, AgNO3, reacts with ferric chloride, FeCl3, to give silver chloride, AgCl, and ferric nitrate, Fe(NO3)3. In a particular experiment, it was plannned to mix a solution containing 25.0 g of AgNO3 with another solution containing 45.0 grams of FeCl3.
a) Write the chemical equation for the reaction.
b) Which reactant is the limiting reactant?
c) What is the maximum number of moles of AgCl that could be obtained from this mixture?
d) What is the maximum number of grams of AgCl that could be obtained?
e) How many grams of the reactant in excess will remain after the reaction is over?
7. / Solid calcium carbonate, CaCO3, is able to remove sulphur dioxide from waste gases by the reaction:
CaCO3 + SO2 + other reactants ------> CaSO3 + other products
In a particular experiment, 255 g of CaCO3 was exposed to 135 g of SO2 in the presence of an excess amount of the other chemicals required for the reaction.
a) What is the theoretical yield of CaSO3?
b) If only 198 g of CaSO3 was isolated from the products, what was the precentage yield of CaSO3 in this experiment?
8. / A research supervisor told a chemist to make 100 g of chlorobenzene from the reaction of benzene with chlorine and to expect a yield no higher that 65%. What is the minimum quantity of benzene that can give 100 g of chlorobenzene if the yield is 65%? The equation for the reaction is:
C6H6 + Cl2 ------> C6H5Cl + HCl
benzene chlorobenzene
9. / Certain salts of benzoic acid have been used as food additives for decades. The potassium salt of benzoic acid, potassium benzoate, can be made by the action of potassium permanganate on toluene.
C7H8 + 2 KMnO4 ------> KC7H5O2 + 2 MnO2 + KOH + H2O
toluene potassium
benzoate
If the yield of potassium benzoate cannot realistically be expected to be more than 68%, what is the minimum number of grams of toluene needed to achieve this yield while producing 10.0 g of KC7H5O2?
10. / Aluminum dissolves in an aqueous solution of NaOH according to the following reaction:
2 NaOH + 2 Al + 2 H2O -----> 2 NaAlO2 + 3 H2
If 84.1 g of NaOH and 51.0 g of Al react:
i) Which is the limiting reagent?
ii) How much of the other reagent remains?
iii) What mass of hydrogen is produced?
11. / Dimethylhydrazine, (CH3)2NNH2, was used as a fuel for the Apollo Lunar Descent Module, with N2O4 being used as the oxidant. The products of the reaction are H2O, N2, and CO2.
i) Write a balanced chemical equation for the combustion reaction.
ii) If 150 kg of (CH3)2NNH2 react with 460 kg of N2O4, what is the theoretical yield of N2?
iii) If a 30 kg yield of N2 gas represents a 68% yield, what mass of N2O4 would have been used up in the reaction?
12. / Magnesium metal reacts quantitatively with oxygen to give magnesium oxide, MgO. If 5.00 g of Mg and 5.00 g of O2 are allowed to react, what weight of MgO is formed, and what weight of which reactant is left in excess?
13. / Adipic acid, C6H10O4, is a raw material for the making of nylon and it can be prepared in the laboratory by the following reaction between cyclohexene, C6H10, and sodium dichromate, Na2Cr2O7 in sulphuric acid.
3 C6H10(l) + 4 Na2Cr2O7(aq) + 16 H2SO4(aq) ------>
3 C6H10O4(aq) + 4 Cr2(SO4)3(aq) + 4 Na2SO4(aq) + 16 H2O
There are side reactions. These plus losses of product during its purification reduce the overall yield. A typical yield of purified adipic acid is 68.6%.
(a) To prepare 12.5 grams of adipic acid in 68.6% yield requires how many grams of cyclohexene?
(b) The only available supply of sodium dichromate is its dihydrate, Na2Cr2O7.2H2O. (Since the reaction occurs in an aqueous medium, the water in the dihydrate causes no problems, but it does contribute to the mass of what is taken of this reactant). How many grams of this dihydrate are also required in the preparation of 12.5 grams of adipic acid in a yield of 68.6%?