Magnesium oxide (MgO) forms when the metal burns in air.(a) If 1.25 g of MgO contains 0.754 g of Mg, what is the massratio of magnesium to oxide? (b) How many grams of Mg are in534 g of MgO?

3.55 An average person inhales roughly 2.5 g of O2 in a minute. How many molecules of oxygen are inhaled in (a) 1 minute, (b) 1 hour, (c) 1 day by an average person?

Nitrogen fixation in the root nodules of peas and other legumes occurs with a reaction involving a molybdenum-containing enzyme named nitrogenase. This enzyme contains two Mo atoms per molecule and is 0.0872% Mo by mass. Calculate the molar mass of the enzyme.

A 1.30 g sample of titanium chemically combines with chlorine gas to form 5.16 g of titanium chloride. (a) What is the empirical formula of titanium chloride? (b) What is the percent by mass of titanium and the percent by mass of chloride in the sample?

In a lab experiment, 8.21 g of phosphorus reacts with bromine to form 71.75 g of phosphorus tribromide. (a) Caculate the precentage by mass of P in phosphorus tribromide. (b) How many grams of bromine reacted?

The poisonous gas hydrogen cyanide (HCN) is producedby the high-temperature reaction of ammonia with methane (CH4). Hydrogen is also produced in this reaction.(a) Write a balanced chemical equation for the reactionthat occurs.(b) Suppose 500.0 g methane is mixed with 200.0 g ammonia. Calculate the masses of the substances present afterthe reaction is allowed to proceed to completion.

5. For the element aluminum, Al: (a) Calculate the number of moles in 7.54 g. (b) Calculate the number of grams in 0.154 mol. (c) How many moles are there in 5.22 x 1022 atoms of the element?

(c) 193.0 g of chlorine dioxide, ClO2 mol

Zinc sulfide (ZnS) occurs in the zinc blende crystal structure.(a) If 2.54 g of ZnS contains 1.70 g of Zn, what is the mass ratioof zinc to sulfide? (b) How many kilograms of Zn are in 3.82 kgof ZnS?

The following quantities are placed in a container: 1.5 × 1024 atoms of hydrogen, 1.0 mol of sulfur, and 88.0 gof diatomic oxygen. (a) What is the total mass in grams for the collection of all three elements? (b) What is the total number of moles of atoms for the three elements? (c) If the mixture of the three elements formed a compound with molecules that contain two hydrogen atoms, onesulfur atom, and four oxygen atoms, which substance is consumed first? (d) How many atoms of each remaining element would remain unreacted in the change described in (c)?