Question 1
1. Convert 1005.3 to exponential form and explain your answer.
2. Convert 4.87 x 10-6 to ordinary form and explain your answer.
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Answer:
1. Convert 1005.3 = larger than 1 = positive exponent, move decimal 3 places = 1.0053 x 103
2. Convert 4.87 x 10-6 =negative exponent =smaller than 1, move decimal 6 places = 0.00000487
Question 2
Using the following information, do the conversions shown below, showing all work:
1 ft = 12 inches 1 pound = 16 oz 1 gallon = 4 quarts
1 mile = 5280 feet 1 ton = 2000 pounds 1 quart = 2 pints
kilo (= 1000) milli (= 1/1000) centi (= 1/100)
deci (= 1/10)
1. 2.73 liters = ? ml 2. 8.6 pts = ? qts
Answer:
1. 2.73 liters x 1000 ml / 1 liter = 2730 ml
2. 8.6 pts x 1 qt / 2 pts = 4.3 qts
Question 3
Do the conversions shown below, showing all work:
1. 248oC = ? oK
2. 25oF = ? oC
3. 175oK = ? oF
Answer:
1. 248oC + 273 = 521 oK oC → oK (make larger) +273
2. 25oF - 32 ÷ 1.8 = -3.88 oC oF → oC (make smaller) -32
÷1.8
3.
175oK - 273 = -98 oC x 1.8 + 32 = -144.4 oF
oK → oC → oF
Question 4
Be sure to show the correct number of significant figures in each calculation.
1. Show the calculation of the mass of a 17.9 ml sample of chloroform with density of 1.49 g/ml
2. Show the calculation of the volume of 19.4 grams of cresol with density of 1.02 g/ml
Answer:
1. M = D x V = 1.49 x 17.9 = 26.7 g
2. V = M / D = 19.4 / 1.02 = 19.0 ml Question 5
1. 1.35601 contains ? significant figures.
2. 0.151 contains ? significant figures.
3. 1.35601 + 0.151 = ? (give answer to correct number of significant figures)
Answer:
1. 1.35601 contains 6 significant figures.
2. 0.151 contains 3 significant figures.
3. 1.35601 + 0.151 = 1.50701 = 1.507 (to the thousands place for 0.151)
Question 6
Classify each of the following as an element, compound, solution or heterogeneous mixture and explain your answer.
1. Honey
2. Hydrogen iodide
3. Tea
Answer:
1. Honey - is not on periodic table (not element) - no element names (not compound) appears to be one substance = Solution
2. Hydrogen iodide - is not on periodic table (not element) - has two element names
= Compound
3. Tea - is not on periodic table (not element) - no element names (not compound) appears to be one substance = Solution
Question 7
Classify each of the following as a chemical change or a physical change
1. A silver spoon forms a black tarnish coating
2. Food is digested
3. Rain freezes on a road on a very cold day
Answer:
1. Silver spoon forms black coating - this is Ag → Ag2S (color change) = chemical change
2. Food is digested - breakdown of carbs, proteins, fats to new materials = chemical change
3. Rain freezes on a road on a very cold day - freezing = physical change
Question 8
Show the full Nuclear symbol including any + or - charge (n), the atomic number (y), the mass number (x) and the correct element symbol (Z) for each element for which the protons, neutrons and electrons are shown - symbol should appear as follows: xZy+/- n
53 protons, 74 neutrons, 54 electrons
Answer:53 protons = I53, 74 neutrons = 127I53, 54 electrons = (+53 - 54 = -1) = 127I53- 1
Question 9
Name each of the following chemical compounds. Be sure to name all acids as acids (NOT for instance as binary compounds)
1. SF6
2. (NH4)3PO4
3. H2S
Answer:
1. SF6 - binary molecular = sulfur hexafluoride
2. (NH4)3PO4 - nonbinary ionic = ammonium phosphate
3. H2S - binary acid = hydrosulfuric acid Question 10
Write the formula for each of the following chemical compounds explaining the answer with appropriate charges and/or prefixes and/or suffixes.
1. Iron (III) cyanide
2. Diiodine pentoxide
3. Potassium phosphide
1. Iron (III) cyanide - Fe+3, CN-1 = Fe(CN)3
2. Diiodine pentoxide - ide = binary, two I, 5 O = I2O5
3. Potassium phosphide - ide = binary K+1, P-3 = K3P
Question 1
Show the calculation of the molecular weight for the following compounds, reporting your answer to 2 places after the decimal.
1. (NH4)2CrO4
2. C8H8NOI Answer:
1. 2N + 8H + Cr + 4O = 152.08
2. 8C + 8H + N + O + I = 261.05
Question 2
Show the calculation of the number of moles in the given amount of the following substances. Report your answerto 3 significant figures.
1. 12.0 grams of (NH4)2CrO4
2. 15.0 grams of C8H8NOI Answer:
1. Moles = grams / molecular weight = 12.0 / 152.08 = 0.0789 mole
2. Moles = grams / molecular weight = 15.0 / 261.05 = 0.0575 mole
Question 3
Show the calculation of the number of grams in the given amount of the following substances. Report your answer to 1 place after the decimal.
1. 1.05 moles of (NH4)2CrO4
2. 1.18 moles of C8H8NOI Answer:
1. Grams = Moles x molecular weight = 1.05 x 152.08 = 159.7 grams
2. Grams = Moles x molecular weight = 1.18 x 261.05 = 308.0 grams Question 4
Show the calculation of the percent of each element present in the following compounds. Report your answer to 2 places after the decimal.
1. (NH4)2SO4
2. C9H9NO3
Answer:
1. %N = 2 x 14.01/132.15 x 100 = 21.20%
%H = 8 x 1.008/132.15 x 100 = 6.10%
%S = 1 x 32.07/132.15 x 100 = 24.27%
%O = 4 x 16/132.15 x 100 = 48.43%
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