Jane performed the following trials in an experiment.

trial 1: heat 80.0 grams of water at 15.0 °c to a final temperature of 65.0 °c.
trial 2: heat 80.0 grams of water at 10.0 °c to a final temperature of 65.0 °c.

which statement is true about the experiments?

a. the same amount of heat is absorbed in both the experiments because the mass is the same.

b. the same amount of heat is absorbed in both the experiments because the final temperature is the same.

c. the heat absorbed in trial 2 is about 1,240 j greater than the heat absorbed in trial 1.

d. the heat absorbed in trial 2 is about 1,674 j greater than the heat absorbed in trial 1.

Calculate the molar mass of aluminum oxide (al2o3). express your answer to four significant figures.

A3.37-mg sample of protein was chemically digested to convert its nitrogen into ammonia and then diluted to 100.0 ml. then 10.0 ml of this solution was placed in a 50-ml volumetric flask and treated with 5 ml of phenol solution plus 2 ml of sodium hypochlorite solution. the sample was diluted to 50.0 ml, and the absorbance at 625 nm was measured in a 1.00-cm cuvette and found to be 0.486. for reference, a standard solution was prepared from 10.0 mg of nh4cl (molar mass = 53.49 grams/mole) dissolved in 1.00 l of water. then 10.0 ml of this standard was placed in a 50-ml volumetric flask, treated in the same manner as the unknown, and the absorbance found to be 0.323. finally, a reagent blank was prepared using distilled water in place of unknown, it was treated in the same manner as the unknown, and the absorbance found to be 0.076. calculate the weight percent of nitrogen in the protein.

Which statement is usually true about the relationship between activation energy and reaction rates? low activation energy barriers result in low rates. high activation energy barriers result in low rates. low activation energy barriers result in no reaction. high activation energy barriers result in no reaction.