A0.450 g sample of impure caco 3 ( s ) is dissolved in 50.0 ml of 0.150 m hcl ( aq ) . the equation for the reaction is caco 3 ( s ) + 2 hcl ( aq ) ⟶ cacl 2 ( aq ) + h 2 o ( l ) + co 2 ( g ) the excess hcl ( aq ) is titrated by 6.45 ml of 0.125 m naoh ( aq ) . calculate the mass percentage of caco 3 ( s ) in the sample.

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.

What is the molar mass of the anhydrous compound? answer using four significant figures. 36.02 g/mol 120.15 g/mol 156.12 g/mol

How many joules of heat are required to raise thetemperature of 750 g of water from 11.0 °c to 19.0 °c?