Can the law of conservation of mass be applied when cooking? In one to two sentences, explain why.
Yes, the law of conservation of mass can be applied when cooking because the total mass of ingredients before cooking is equal to the total mass of the final dish after cooking, with no mass being created or destroyed in the process.
The molar mass of ammonium acetate is 77.083 g/mol. A student uses 0.100 mol of ammonium acetate in a chemical reaction. The student claims that the reaction uses
(0.1mol)(77.083 g/mol) = 7.71 g of ammonium acetate, which has
(7.71)(6.022 * 10 ^ 23) = 4.64 * 10 ^ 24 molecules. In one to two sentences, explain the mistake that the student made and determine the correct number of molecules of ammonium acetate used in the reaction.
The mistake the student made is that they incorrectly calculated the number of molecules of ammonium acetate by using Avogadro's number with the total mass of the compound instead of the molar mass. The correct calculation would be (0.1 mol) * (6.022 * 10^23 molecules/mol) = 6.022 * 10^22 molecules of ammonium acetate used in the reaction.
A chemist will use a sample of 30 g of ethanol (C*H_{3}*C*H_{2}*OH) in an experiment. In one to two sentences, make and justify a claim about the number of moles of ethanol the chemist will use.
Element | Molar Mass (g/mol)
_________________________
carbon | 12.01
Hydrogen | 1.01
oxygen | 16.00
The chemist will use approximately 0.67 moles of ethanol in the experiment. This claim is justified by dividing the mass of the sample (30 g) by the molar mass of ethanol (46.08 g/mol), which yields approximately 0.65 moles of ethanol.
Are you sure?
Apologies for the miscalculation. Let's reevaluate the number of moles of ethanol the chemist will use:
Molar mass of ethanol (C2H5OH) = (2 * 12.01 g/mol) + (5 * 1.01 g/mol) + (1 * 16.00 g/mol) = 46.08 g/mol
Number of moles = Mass / Molar mass = 30 g / 46.08 g/mol ≈ 0.65 moles
Therefore, the correct claim is that the chemist will use approximately 0.65 moles of ethanol in the experiment.