Chem121.F18.E1PK.pdf - Chemistry 121 Exam 1 Practice Fall...

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Chemistry 121 Exam 1 Practice Fall 2018 The following examination contains 33 questions worth 3.3 points each Name KEY °F = 1.8°C + 32 K = C + 273 1 mile = 1.609 km 1 foot = 0.3048 m 1 kg = 2.205 lb 1 ton = 2000 lb (exact) E = (S.H.)(m)( t) 1. Which of the following is not a chemical change? a. Brush drying on a hot day b. Spark igniting brush c. Wildfire generating CO 2 , H 2 O, and smoke d. Cool, wet air slowing the wildfire The key word is drying evaporation of water is a physical change 2. As a clear red liquid sits at room temperature, evaporation occurs until only red solid remains. Was the original liquid an element, a compound, or a mixture? If one substance evaporates under a given set of conditions and one substance does not, then it had to be a mixture to begin with (homework problem) 3. Which of the following best describes oil & vinegar salad dressing? (a) & (c) Oil and water don’t mix (vinegar is water based). If emulsifying agents were included it would potentially be more homogenous, but as simply oil and vinegar heterogeneous big time. Obviously, as a 2 component substance, it cannot be pure
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4. Ammonium sulfate has the formula (NH 4 ) 2 SO 4 . How many hydrogen atoms are in each ammonium sulfate? Subscripted number apply to whatever atom preceded it; if what preceded it was in parentheses, it applies to everything within the parentheses 5. Calcium phosphate has the formula Ca 3 (PO 4 ) 2 . How many total atoms are in each calcium phosphate?
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