Chem- Exam 1

Conversions

1 gram= 10 deci

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)

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)

Using the following information, do the conversions shown below, showing all work: 2.73 liters = ? ml 8.6 pts = ? qts

1. 2.73 liters x 1000 ml / 1 liter = 2730 ml 2. 8.6 pts x 1 qt / 2 pts = 4.3 qts

Do the conversions shown below, showing all work: 1. 248oC = ? oK 2. 25oF = ? oC 3. 175oK = ? oF

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

Classify each of the following as an element, compound, solution or heterogeneous mixture and explain your answer. 1. Honey 2. Hydrogen iodide 3. Tea

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

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

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

1. M = D x V = 1.49 x 17.9 = 26.7 g 2. V = M / D = 19.4 / 1.02 = 19.0 ml

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

1. SF6 - binary molecular = sulfur hexafluoride 2. (NH4)3PO4 - nonbinary ionic = ammonium phosphate 3. H2S - binary acid = hydrosulfuric acid

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

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

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

Convert 1005.3 to exponential form and explain your answer.

Convert 1005.3 = larger than 1 = positive exponent, move decimal 3 places = 1.0053 x 103

Convert 4.87 x 10-6 to ordinary form and explain your answer

Convert 4.87 x 10-6 =negative exponent =smaller than 1, move decimal 6 places = 0.00000487

Conversion Chart

Look at picture