In an experiment 16.81 +/- 0.02 grams of hydrogen peroxide chemically decomposes into the products water and oxygen gas. The measured mass of oxygen gas produced in the reaction is 8.854 +/- 0.003 grams. Report the mass of water produced to the correct number of significant digits (Do not perform any calculation involving the estimates of uncertainties in the measurements.)

Is the answer 7.96 grams?? Is it the correct num of sig figs??

Yes, 7.96 g is correct and the correct number of s.f. BECAUSE,

16.81 - 8.854 = 7.956 g. The least sig number is 16.81 (two places to the right of the decimal) and when we subtract, we may have in the answer no more than two places to the right of the decimal. Thus, 7.956 rounds to 7.96 which has two places to the right of the decimal.

To determine the mass of water produced, we need to use the law of conservation of mass, which states that matter is neither created nor destroyed in a chemical reaction. Therefore, the total mass of the reactants (hydrogen peroxide) must be equal to the total mass of the products (water + oxygen gas).

Given that the mass of hydrogen peroxide (H2O2) is 16.81 ± 0.02 grams and the mass of oxygen gas (O2) is 8.854 ± 0.003 grams, we can find the mass of water (H2O) by subtracting the mass of oxygen gas from the total mass of the reactant.

Total mass of reactant (H2O2) = 16.81 ± 0.02 grams
Mass of oxygen gas (O2) = 8.854 ± 0.003 grams

Mass of water (H2O) = Total mass of reactant - Mass of oxygen gas
= 16.81 grams - 8.854 grams
= 7.956 grams

Since the given mass of oxygen gas has the uncertainty of ± 0.003 grams, the resulting mass of water should also be reported with the same significant figures as the uncertainty. Therefore, the correct mass of water, considering the significant figures, is 7.96 grams.