Most people find waterbeds uncomfortable unless the water temperature is maintained at about 85 °f. unless it is heated, a waterbed that contains 892 l of water cools from 85 °f to 72 °f in 24 hours. estimate the amount of electrical energy required over 24 hours, in kwh, to keep the bed from cooling. note that 1 kilowatt-hour (kwh) = 3.6 × 106 j, and assume that the density of water is 1.0 g/ml (independent of temperature). what other assumptions did you make? how did they affect your calculated result (i. e., were they likely to yield "positive" or "negative" errors)?

One way in which the useful metal copper is produced is by dissolving the mineral azurite, which contains copper(ii) carbonate, in concentrated sulfuric acid. the sulfuric acid reacts with the copper(ii) carbonate to produce a blue solution of copper(ii) sulfate. scrap iron is then added to this solution, and pure copper metal precipitates out because of the following chemical reaction: (s) (aq) (s) (aq) suppose an industrial quality-control chemist analyzes a sample from a copper processing plant in the following way. he adds powdered iron to a copper(ii) sulfate sample from the plant until no more copper will precipitate. he then washes, dries, and weighs the precipitate, and finds that it has a mass of .