A metal oxide contains 74.2% metal by mass. Determine the identity of the metal oxide.

You have a pure sample of the antiseptic aminacrine, C13H10N2. Calculate the mass in grams of 0.06500 mol aminacrine. Calculate the number of aminacrine molecules in a 0.2480-g sample. Calculate the number of nitrogen atoms in this 0.2480-g sample. Calculate the mass of N in 100. g aminacrine.

What number of molecules (or formula units) are present in 1.00 g of each of the compounds in Exercise 52?

Atomic masses are relative masses. What does this mean?

opical hydrocortisone is often used to treat a variety of skin conditions, such as insect bites, eczema, and rashes. Each molecule of hydrocortisone contains 21 atoms of carbon (plus other atoms). The mass percentage of carbon in hydrocortisone is 69.5 8%. What is the molar mass of hydrocortisone?

Hemoglobin is an iron-containing protein (molar mass 64,458 g/mol) that is responsible for oxygen transport in our blood. Hemoglobin is 0.35% iron by mass. Calculate how many iron atoms are in each hemoglobin molecule.

A substance X2Z has the composition (by mass) of 40.0% X and 60.0% Z. What is the composition (by mass) of the compound XZ2?

Arrange the following substances in order of increasing mass percent of carbon. a. caffeine. C8H10N4O2 b. sucrose, C12H22O11 c. ethanol, C2H5OH

There are two binary compounds of mercury and oxygen. Heating either of them results in the decomposition of the compound, with oxygen gas escaping into the atmosphere while leaving a residue of pure mercury. Heating 0.6498 g of one of the compounds leaves a residue of 0.6018 g. Heating 0.4172 g of the other compound results in a mass loss of 0.016 g. Determine the empirical formula of each compound.

2.37 Why are empirical formulas preferred for describing polymer molecules?