1,001 Chemistry Practice Problems For Dummies (2014)

Part I. The Questions

Chapter 3. Matter and Energy

Chemists deal with matter. Matter occurs in many forms with certain observable properties. One easily observable property of matter is density, which is the mass of a sample of matter divided by its volume. It’s possible to alter matter either physically or chemically. All alterations involve energy.

The Problems You’ll Work On

In this chapter, you work with matter and energy in the following ways:

check Describing phases of matter

check Classifying matter as substances and mixtures

check Understanding properties of matter

check Determining density

check Calculating energy and temperature

What to Watch Out For

Remember the following when working on matter and energy:

check Know the properties of solids, liquids, and gases on microscopic and macroscopic levels.

check Remember that a density must have a mass unit divided by a volume unit.

Phases of Matter and Phase Changes

136–143 Check your understanding of phases of matter and phase changes.

136. Which phase of matter doesn’t have a definite shape or a definite volume under normal conditions?

137. Which phase of matter has a definite shape and a definite volume?

138. Which phase of matter has a definite volume but takes the shape of the container that it’s in?

139. When matter changes from a liquid to a solid, which phase change is it going through?

140. When matter changes from a gas to a liquid, which phase change is it going through?

141. When matter changes from a liquid to a gas, which phase change is it going through?

142. When matter changes from a solid to a gas without becoming a liquid in between, which phase change is it going through?

143. When matter changes from a gas to a solid without becoming a liquid in between, which phase change is it going through?

Classifying Substances and Mixtures

144–152 Classify each type of matter as a pure substance or mixture. Then classify each pure substance as an element or compound and each mixture as homogeneous or heterogeneous.

144. Gold

145. Table sugar

146. Fresh air

147. Oxygen

148. Vegetable soup

149. Fruit salad

150. Calcium

151. Concrete

152. Smog

Properties of Matter

153–165 Check your understanding of the properties of matter.

153. Which type of property of matter doesn’t depend on the amount of the substance that’s present?

154. Which type of change involves a change in the form of a substance?

155. Which type of change involves a change in the identity of a substance?

156. Which type of property of matter depends on exactly how much of the substance is present?

157. Density is a(n) _______________ (chemical/extensive physical/intensive physical) property.

158. Length is a(n) _______________ (chemical/extensive physical/intensive physical) property.

159. Color is a(n) _______________ (chemical/extensive physical/intensive physical) property.

160. Flammability is a(n) _______________ (chemical/extensive physical/intensive physical) property.

161. Mass is a(n) _______________ (chemical/extensive physical/intensive physical) property.

162. Odor is a(n) _______________ (chemical/extensive physical/intensive physical) property.

163. Ductility is a(n) _______________ (chemical/extensive physical/intensive physical) property.

164. Electrical conductivity is a(n) _______________ (chemical/extensive physical/intensive physical) property.

165. Solubility is a(n) _______________ (chemical/extensive physical/intensive physical) property.

Calculating Density

166–174 Perform the density calculations. Be sure to round your answers to the correct number of significant figures. (See Chapter 2 for significant figure problems.)

166. In grams per cubic centimeter, what is the density of a substance with a mass of 57.5 g and a volume of 5.0 cm3?

167. A 25.0-mL sample of a liquid has a mass of 22.1 g. What is the liquid’s density in grams per milliliter?

168. The mass of 2.00 m3 of a gas is 3,960 g. What is the density of this gas in kilograms per cubic meter?

169. What is the mass, in grams, of 0.200 L of a saltwater solution with a density of 1.2 g/mL?

170. Aluminum is a metal that has a density of 2.7 g/cm3. How many grams are in a solid cube of aluminum that measures 3.00 cm per side?

171. If a block has a length of 5.0 cm, a width of 3.0 cm, a height of 2.0 cm, and a mass of 120. g, what is the block’s density?

172. What is the mass, in kilograms, of 1.5 L of solid gold? Solid gold has a density of 19.3 g/cm3.

173. If a sample of gasoline has a mass of 77.0 g and a density of 0.71 g/mL, what is the volume of the gasoline in milliliters?

174. What is the length of one side of a metallic cube that has a density of 10.5 g/cm3 and a mass of 672 g?

Working with Energy

175–190 Assess your understanding of energy and related calculations.

175. Which unit represents the amount of energy necessary to raise the temperature of 1 g of water by 1°C?

176. Which SI unit is used to express the heat content of a mole of a chemical?

177. Which unit is used to express the energy found in food?

178. A bucket on a ladder has __________ (kinetic/potential) energy, which is the energy of __________ (motion/position).

179. A rolling ball has __________ (kinetic/potential) energy, which is the energy of __________ (motion/position).

180. Fuels contain __________ (moving/stored) energy, which is __________ (kinetic/­potential) energy.

181. How many kilocalories are in 25,970 J?

182. How many joules are in 3.1 × 108 kilocalories?

183. Average kinetic energy can be measured in what units?

184. If water is heated by 80.0°C, how many ­kelvins is that?

185. The melting point of sodium chloride is 1,074 K. What temperature is this in degrees Celsius?

186. Liquid oxygen boils at –183°C. How many degrees Fahrenheit is this?

187. Normal human body temperature is considered to be around 98.6°F. How many degrees Celsius is this?

188. Adding dry ice to acetone brings the temperature down to –78°C. What is this ­temperature in degrees Fahrenheit?

189. One summer day, the temperature was recorded as 113°F. How many kelvins is this?

190. Room temperature is about 300. K. How many degrees Fahrenheit is this?