Ch1 Example Problems Answers

Ch1 Example Problems Answers - HODSON CHE 1301 Ch1 Example...

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HODSON CHE 1301 Ch1 Example Problems Answers The following problems are taken from old exams…… 1) Which of the following is a heterogeneous mixture? A) vinegar B) water C) root beer float D) sugar E) vegetable oil Answer: C Explanation: A heterogeneous mixture has different properties and composition in different parts of the mixture. Imagine a beaker (or glass) containing samples of each of the above . ... vinegar from the top of the glass would be exactly the same as vinegar from any other part of the glass. The same goes for B and E. In a root beer float, you could take a drink from the top of the glass and just end up getting ice cream (yum); taking a sip through a straw from the bottom of the glass would just give you root beer. The mixture hence varies. 2) What is the mass, in lb, of a 225 g object? (note that 1 lb = 0.4536 kg) A) 0.4956 B) 0.496 C) 0.500 D) 0.49559 E) none of these Answer: B Explanation: We must convert the value of 225 g to a number of lbs, and to do this we need a relationship between the two units. We may not know a direct relationship, but we can work our way from the given value in grams to a number of kilograms easily, and once we are in kilograms, we can write a second conversion factor using the given equivalence to convert between kg and lb. 225 g × (1 kg / 1000 g) × (1 lb / 0.4536 kg) = 0.496 lb Note that we have only 3 significant figures, as the data with the least number of s.f.s is 225 g. 3) Which of the following processes does not represent a chemical change? A) reaction of sodium metal with water to give hydrogen gas and sodium hydroxide B) dissolving sugar in water C) souring of milk D) leaves changing color E) iron rusting Answer: B Explanation: In a chemical change, we start off with one or more substances and end up with one or more other substances being formed. We are basically just
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rearranging the way that the atoms are joined together. In answers A, C, D, and E, we start with one substance or substances and end up with something different. In B, we start with sugar and water, and end up with sugar and water (perfectly mixed together (a homogenous solution)), so we have not change the substances involved. 4) Which of the following does not represent a physical property? A) color
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This note was uploaded on 12/18/2009 for the course CHE 1301 taught by Professor Klausmeyer during the Spring '08 term at Baylor.

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Ch1 Example Problems Answers - HODSON CHE 1301 Ch1 Example...

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