The following quiz contains 21 questions valued at 1.0 point/question. Density (ethanol) = g/ml 2.54 cm/in kg = lb meter = 39.

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1 Chemistry 121 Quiz I Practice Spring 2018 The following quiz contains 21 questions valued at 1.0 point/question Name KEY Density (ethanol) = g/ml 2.54 cm/in kg = lb meter = inches 1 yd = 3 ft 36 inches = 1 yard 1 mile = km g = 1 lb 1 fl.oz. = ml 1. Which of the following is a physical change and which is a chemical change? Use PC for physical change or CC for chemical change. a. Boiling water PC b. Decomposing water by passing electric current through it CC c. Dissolving sugar in water PC d. Exploding of potassium metal when placed in water CC 2. Which of the following best describes mayonnaise? a. Heterogeneous mixture b. Homogeneous mixture c. Compound d. Element For questions like this, visual uniformity is sufficient (certainly colloidal dispersions and molecular solutions fit within this definition being uniform microscopically and beyond 3. Which of the following best describes chunky salsa (the food not the dance)? a. A homogenous element b. A homogeneous compound c. A heterogeneous element d. A heterogeneous compound e. A heterogeneous mixture

2 4. Which of the following defines a colloidal dispersion? a. Particle size 2 Å b. Particle size 2 nm c. 2 nm particle size.5 m d. Particle size.5 m 5. Please provide the name for a colloidal dispersion of a liquid dispersed into a much larger volume of gas Answer: [Liquid] Aerosol 6. Which of the following is the symbol for sodium a. S b. So c. Si d. Ni e. Na Bonus (1 EC): Which of the above symbols does not correspond to any element? Answer: So S = sulfur, Si = silicon, Ni = nickel, So = a needle pulling thread 7. Please provide the symbols for the following elements a. Argon Ar b. Arsenic As 8. Give the names corresponding to the following symbols a. Xe Xenon (warrior element) b. Kr Krypton

3 9. How many g (mcg) are equivalent to a mg? a g/mg b g/mg c g/mg d g/mg Micro is 1000x smaller than milli so you would need 1000 of them for the same quantity 10. How many km are equivalent to a mm? a. 1.0 x 10 6 km/mm b. 1.0 x 10 3 km/mm c. 1.0 x 10-3 km/mm d. 1.0 x 10-6 km/mm Kilometer is 1000x larger than the meter, which in turn is 1000x larger than millimeter, so you would need of the kilometer to correspond to a mm scales were tested against a g mass standard. Of the following sets of measurements, which has the greatest accuracy? Scale 1 Scale 2 Scale 3 Scale g g g g g g g g g g g g g g g g a. Scale 1 b. Scale 2 c. Scale 3 d. Scale 4 Scale 2 is consistent with the standard to 2 significant figures (take the average). Scale 1 is obviously most precise (repeatable measurements very nearly to the mg place) but deviates by > 0.1 g from the standard 12. How many significant figures are in g? a. 1 b. 2 c. 3 d. 4 e. 5

4 13. Express g in scientific notation. Answer: 7.1 x 10-3 g Notice the 2 significant figures in the lead term 14. Express g using the appropriate metric prefix. Answer: 7.1 mg milli = Please carry out the following calculation, retaining the correct number of significant figures and showing units. (2.231 g g g) 7.1 ml 2.231? 1.00?? g 7.46 g 7.1 ml Answer: 1.0 g/ml Addition and subtraction make certain the units are the same, stack em up, and see where the uncertainty begins. Multiplication and division hold answer to same significance as the worst measurement that went into it 16. A metric ton is 1000 kg. A British ton is 2000 pounds. What is the difference in mass between a British and metric ton? a. 2.2 pounds b. 200 pounds c. 220 pounds d pounds 1000 kg(2.205 lb/kg) = 2,205 lb 2,205 lb 2000 lb = 205 lb 17. The mass of premature babies is customarily determined in grams. If a premature baby weighs 1550 g, what is its mass in pounds? Please show your work g(lb/453.6 g) = 3.42 lb

5 18. An individual weighs 83.2 kg and is 1.92 m tall. What are the person s equivalent measurements in pounds and feet? Please show your work kg(2.205 lb/ft) = 183 lb 1.92 m(39.37 in/m)(ft/12 in) = 6.30 ft or Which is a longer race, the 800 m (exactly) or the half mile (0.5 mile exactly)? Please show your work mi(1609 m/mi) = 804 m 804 m > 800 m 20. What is the mass associated with 50.0 ml pure ethanol? a g b g c g d g 50.0 ml(0.789 g/ml). As a mental check, if the density were 1.00 g/ml it would weigh 50 g and the density is less, so the mass should be less 21. Ethanol (CH 3 CH 2 OH) has a molar mass = 46 g/mole. How many grams of ethanol are required for 2.0 mol of ethanol? a. 2.3 g b. 9.2 g c. 23 g d. 92 g 2.0 mol(46 g/mol). Bonus (1 EC): Mercury has a density of 13.6 g/ml at 20 o C. What is the mass in pounds of one U.S. pint (16 fl. oz. exactly) of mercury? Please show your work fl oz(29.57 ml/fl. oz)(13.6 g/ml)(lb/453.6 g) = 14.2 lb ½ the value we obtained in class as one U.S. pint is defined as ½ a U.S. quart