STUDY PROBLEMSCHEMISTRY 60CHAPTERS 1-7

PRACTICE PROBLEMS C1Show your work for the following questions on the back. Always give the correct

significant figures.

1. Express each of the following numbers in scientific notation & 3 significant figures.

A) 6545490087 _______ C) 0.0002368 _______

B) 0.000001243 _______ D) 94560 _______

2. 0.00496 - 0.00298 = ________________

3. (3.36-5.6) / (82.98 + 2.4) = ______________________

4. 4.45 x 10- 23 / 8.345 x 10-53 = ________________

5. [(26.7 x 10-8) (47 x 1013)]4 / (8.54 x 1017)1/2 = __________

6.55 x 109

1.24 x 10-6

2.37 x 10-4

9.46 x 104

1.98 x 10 -3

STUDY PROBLEMS C1A study of gemstones and dimensional analysis: The basic unit for gemstones is the

carat. One carat is equal to 200 milligrams.

1. The Star of India sapphire (Al2O3, corundum) weighs 1.126 x 105 mg. What is the weight of the gemstone in carats?

2. The Cullinan Diamond was cut into nine major stones and 96 smaller brilliants. The total weight of the cut stones was 1063 carats, only 35.0% of the original weight! What weight (in milligrams) of the Cullinan Diamond was not turned into gemstones?

3. D.J. promised to bake 200 dozen cookies and deliver them to a bake sale. If each cookie weighs 3.5 ounces, how many grams will 200 dozen cookies weigh? 1 oz. is the same as 28.3495 g.

4. One box of envelopes contains 500 envelopes. A case of envelopes contains 28 boxes of envelopes and cost $123.49. What is the cost, in cents, of an envelope?

How many meters are in 2608 centimeters?

SIMPLE MEASUREMENT CONVERSIONS C2

How many milliliters are in 2.96 liters?

How many kilograms are equal to 0.3648 grams?

STUDY PROBLEMS C2_____1. Water boils at 212 oF, what is the boiling point of

water in oC? What is this temperature in Kelvin?

_____2. Convert 25.0 ng to cg

_____3. Convert 25.0 kJ to cal

_____4. Convert 25.0 lb to mg

_____5. Convert 25.0 ft3 to L

6. How many liters of gasoline will be used to drive 725 miles in a car that averages 27.8 miles per gallon?

7. What is the percent of salt in a saltwater solution if 246.99 cm3 of sodium chloride was added to 4.00 gal of pure DI water?

STUDY PROBLEMS C28. If 2830.5 cg of a sample of haematite iron ore [iron (III) oxide, Fe203] were dissolved in concentrated hydrochloric acid and then the solution was diluted to 250 dm3. What is the mass of ore in pounds and what volume (in qt) of solution was made?

9. An instructor gives a sample of powered metal to each of four students (W, X, Y, & Z), and they weigh the samples on different balances. Their results for three trials are as follows. The true value is 1.921 x 10-2 lbs.

A) Calculate the average mass for each data set with the correct significant figures.

B) Which student was the most accurate in weighing? C) Which student was the most precise? D) Which student had the best combination for accuracy and

precision? Student Trial 1 Trial 2 Trial 3 Average

W 8.72 g 8.7810 g 8.6 g

X 8.50 g 8.48 g 8.511 g

Y 8.56 g 8.7770 g 8.830 g

Z 8.4100 g 8.720 g 8.550 g

Study Problem on Density Record your final answer on this sheet and show all of your work on the back. Use scientific

notation when necessary and always given your answers with the appropriate significant

figures.

• 1. Calculate the volume, in liters, of a box that is 346 mm long by 6.75 cm wide by 17.88 in high.

• 2. Calculate the density of a liquid if 63.76 mL of the liquid has a mass of 3456. cg.

• 3. What volume of mercury will have a mass of 4.0 kg if it has a density of 13.6 g/mL?

•  4. What is the density (in g/mL) of a substance that weighs 9.272 lb. and occupies a volume of 12.48 qt.

• 5. The mass of an irregular shaped object was measured to be 35.58 g. A student fills a 50.0 mL graduated cylinder with 23.0 mL of water, then places the object into the graduated cylinder. The new volume is 47.5 mL. Calculate the density of the object.

• 6.  A piece of indium weighing 9.942 g is placed in 39.7 cm3 of ethyl alcohol (density = 0.798 g/mL) in a graduated cylinder. The alcohol level increases to 48.8 cm3. The density of indium based on this data is? Is the measurement accurate?

STUDY PROBLEMS C31. Classify the following as an element, compound, or mixture

(heterogeneous or homogeneous).

• _____ wine _____ root beer• _____ penny _____ table salt• _____ Bleach _____ wood• _____ diamond _____ vinegar2. A clear blue liquid in an open beaker was left in the hood. After 1 week,

the beaker contained only blue crystals. The original liquid can be classified as a(n) ______________.

3. Classify the following as physical or chemical changes.

• _____ perspiration _____ sugar dissolving• _____ fermentation _____ aging

STUDY PROBLEMS ON HEAT ENERGY• _____1. A 250.0 g metal bar requires 5.866 kJ to change its temperature

from 22.0oC to 100.0oC. What is the specific heat of the metal in J/goC?

• _____2. How many joules are required to lower the temperature of 100.0 g of iron from 75.0 oC to 25.0 oC?

• _____ 3. If 40.0 kJ were absorbed by 500.0 g H2O at 10.0 oC, what would be the final temperature of the water?

• _____ 4. A 250 g of water at 376.3 oC is mixed with 350.0 mL of water at 5.0 oC. Calculate the final temperature of the mixture.

• _____5. A 400 g piece of gold at 500.0oC is dropped into 15.0 L of water at 22.0oC. The specific heat of gold is 0.131 J/goC or 0.0312 cal/goC. Calculate the final temperature of the mixture assuming no heat is lost to the surroundings.

STUDY PROBLEMS ON LAWS1. Pure gold is too soft a metal for many uses, so it is alloyed to give it

more mechanical strength. One particular alloy is made by mixing 29.17 g of gold, 3.81 grams of silver, and 5.91 g of copper. What carat gold is this alloy if pure gold is considered to be 24 carat?

2. If 9.0 ounces of a meat sample contains 21.9 g of fat, what percentage of fat is present?

3. How many grams of CuO can be obtained from 1.80 g of copper?

4. When aluminum combines with bromine gas, they produce the substance aluminum bromide, AlBr3.

a)Write a chemical equation describing this reaction.b) If 56.88 g of aluminum bromide is formed from 5.75 g of aluminum,

how many grams of bromine was needed?c) Since 56.88 g of aluminum bromide is formed from 5.75 g of

aluminum, how many grams of bromine will combine with 16.50 g of aluminum?

STUDY PROBLEMS on ISOTOPES_______1. The element with atomic number 53 containsa) 53 neutrons b) 53 protons C) 26 neutrons & 27 protons d) 26 protons & 27 neutrons

_______2. The mass of one atom of an isotope is 9.746 x 10-23 g. One atomic mass unit has the mass of 1.6606 x 10-24 g. The atomic mass of this isotope is

a) 5.870 amu b) 16.18 amu c) 58.69 amu d) 1.627 amu

108

_______3. The number of neutrons in an atom of 47 Ag is

a) 47 b) 108 c) 155 d) 61

27

_______4. The number of electrons in an ion of 13 Al3+ is

a) 13 b) 10 c) 27 d) 14

_______5. What is the relative atomic mass of boron if two stable isotopes of boron have the following mass and abundance:

10.0129 amu (19.91%) & 11.0129 (80.09%)a) 10.81 amu b) 10.21 amu c) 10.62 amu d) 10.51 amu

STUDY PROBLEMS on IONIC COMPOUNDSBelow the formula, give the systematic name for the following compounds. If a common name exist, write it below the systematic name.

1. CaI2 2. Cs2S 3. Al2S3

4. CdI2 5. SnCl2 6. Zn(NO3)2

7. Fe2O3 8. Fe(OH)2 9. PbSO4

  

STUDY PROBLEMS on NAMINGBelow the name, write the formula for the following compounds.

a) Barium oxide b) Sodium bromide  

c) Copper(I) oxide d) Iron(II) chloride

e) Potassium nitrite f) Calcium hydroxide

g) Silver nitrate h) Ammonium chloride

i) Lithium phosphate j) Sodium nitrite

k) Sodium bicarbonate l) Calcium Carbonate

m) Sodium sulfate n) Iron(III) hydroxide

o) Copper(II) hypochlorite p) Sodium sulfite

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STUDY PROBLEMS on MOLE1. If 16.054 g of calcium chloride reacted with 25.004 g of sodium

carbonate, how many moles of each will be reacting?

2. How many moles of oxygen are contained in 54.78g of Cu(NO3)2?

3. Which contains the larger number of molecules?

a) 125.0 g HCl b) 15.0 g C6H12O6 c) 170.0 g of I2

4. How many grams of silver are contained in 0.754 mol of AgNO3?

a) 0.488 g b) 81.3 g c) 128g d) 170g

5. 7.0 g of nitrogen (N2) contains

a) 7.0 atoms of N c) 3.0 x 1023 atoms of N

b) 0.25 mole of N d) 7.0 atomic masses of N

6. How many atoms are in 56.9 g of potassium nitrite?

7. Calculate the mass of 3.45 x 10-25 molecules of methane.

STUDY PROBLEMS on % composition1. A 5.016 g sample of chromium, Cr, combined with oxygen to give 7.333 g of an oxide compound. Calculate the percent composition of this compound.

2. Calculate the percent composition. K2CrO4 K =_____ Cr =_____ O = _____ K2Cr2O7 K =_____ Cr =_____ O = _____

3. How many grams of aluminum will combine with 3.67 g of sulfur to form Al2S3?

STUDY PROBLEMS on empirical formula1. A sample of a compound weighing 4.18 g contains

1.67 g of sulfur and the rest is oxygen. What is the empirical formula?

2. What is the empirical formula of the compound whose composition is 28.7% K, 1.4% H, 22.8 % P, and 47.1% O?

3. A compound contains 92.3% C and 7.7% H and has a molar mass of 78.0 g/mol. Determine the molecular formula.

STUDY PROBLEMS on equationsBalance the following molecular equations then write both the ionic & net ionic equations. Describe if electrolytes are involved, or combustion, or gas formation.

1. __NaBr(aq) + __Cl2(g) __ NaCl(aq) + __Br2(l)

2. __SbCl3(aq) + __Na2S(aq) __Sb2S3(s) + __NaCl(aq)

3. __Mg(OH)2(aq) + __ H2SO4(aq) __ H2O(l) + __MgSO4(aq)

4. __C2H4(g) + __O2(g) __CO2(g) + __H2O(g)

5. __Na2SO4(aq) + __AlCl3(aq) __Al2(SO4)3(aq) + __NaCl(aq)

STUDY PROBLEM on chemical reactionsWrite the following as balanced chemical equations then classify each reaction.

1. Solid mercuric oxide decomposes at high temperatures to form metallic mercury and oxygen.

2. Aqueous lead(II) nitrate reacts with aqueous magnesium bromide to produce the insoluble salt lead(II)bromide and soluble magnesium nitrate.

3. At room temperature, aqueous ammonium carbonate is added to hydrochloric acid to produce aqueous ammonium chloride, water and carbon dioxide.

4. Hydrochloric acid is poured over tin metal producing hydrogen gas and tin (IV) chloride.

5. The combustion of ethanol, C2H5OH, results in the production of carbon dioxide and water.

STUDY PROBLEM on predicting productPREDICT THE PRODUCT THEN WRITE A BALANCED EQUATION FOR EACH REACTIONS.

1. The reaction between lead (II) acetate and ammonium carbonate solutions results in the formation of a white solid.

2. An zinc metal wire is dipped in hydrobromic acid.

3. The decomposition of sulfurous acid.

4. Sodium hydroxide solution is added to sulfuric acid.

5. Solid tin(II) sulfide is added to hydroiodic acid.