Exam 3: Stoichiometry: Mass, Formulas, and Reactions

Like many metals, manganese reacts with halogens to give metal halides. How many grams of MnF₃ can be produced using excess fluorine and 5.49 g of Mn? (molar masses: Mn = 54.9 g/mol, F = 19.0 g/mol) 2Mn(s) + 3F₂(g) $\rightarrow$ 2MnF₃(s)

Air bags in cars inflate when an electrical spark activates sodium azide (NaN₃) so that it decomposes to sodium metal, Na, and nitrogen gas, N₂. In the balanced reaction equation, how many moles of nitrogen gas are formed for each mole of sodium azide?

Phthalocyanine is a large molecule used in printing inks and dyes for clothing due to its insolubility in most solvents, its chemical stability, and its intense blue color. Elemental analysis showed that it consists of 74.69% C, 3.525% H, and 21.77% N, and has a molar mass of 514.54 g/mol. What is the molecular formula for phthalocyanine?

The space shuttle uses liquid hydrogen and liquid oxygen to produce thrust for liftoff in the following reaction. If the liquid oxygen supply is set to provide 420 kg/s during a launch, what does the rate of liquid hydrogen supply need to be in kilograms per second? 2H₂(l) + O₂(l) $\rightarrow$ 2H₂O(g)

If the combustion of fossil fuels adds about 5 *10¹² kg of carbon to the atmosphere as CO₂ each year, how much oxygen is required to produce this amount of carbon dioxide?

Identify the correct statement regarding the mole.

Which statement about the following chemical reaction is not correct? 3H₂ + N₂ $\rightarrow$ 2NH₃

Even though lead is toxic, lead compounds were used in ancient times as white pigments in cosmetics. What is the percentage of lead by mass in lead(IV) carbonate, Pb(CO₃)₂?

Diesel fuel for automobiles and trucks is a mixture of hydrocarbons that can be modeled by C₁₆H₃₄. Write the balanced reaction equation for the combustion of C₁₆H₃₄, and report the sum of the stoichiometric coefficients.

Which one of the following samples contains the fewest number of molecules? H is used as the symbol for hydrogen-1, and D is used as the symbol for hydrogen-2.

A self-contained breathing apparatus contains 25.0 g KO₂ that is used to treat 45.0 g CO₂ to regenerate oxygen. How many grams of CO₂ were not converted to oxygen because of the limited amount of potassium superoxide present? 4KO₂(s) + 2CO₂(g) $\rightarrow$ 2K₂CO₃(s) + 3O₂(g)

You are given a liquid sample that contains either methanol (CH₃OH), ethanol (CH₃CH₂OH), or a mixture of both. You use combustion analysis of a 0.336 g sample and obtain 0.462 g of CO₂. What did you learn about your sample?

A reaction vessel contains equal masses of iron and oxygen. How much FeO could theoretically be produced?

In the summer of 2010, platinum (195.078 g/mol) sold for $1,500/oz. One ounce is equal to 28.35 g. How many platinum atoms could you buy with a penny ($0.01)?

The average adult exhales about 1.0 kg of carbon dioxide each day. How much glucose (C₆H₁₂O₆, 180 g/mol) is consumed to make that much carbon dioxide?

Platinum (195.078 g/mol) once sold for $560/oz. One ounce is equal to 28.35 g. How many platinum atoms could you buy with a penny ($0.01)?

When are an empirical formula and a molecular formula the same?

A compound known to contain platinum, nitrogen, and hydrogen was analyzed and found to contain 74.1% Pt and 21.3% N; the remainder was hydrogen. What is the empirical formula for the compound?

How many hydrogen atoms are there in 36.0 g of water (H₂O)?

A fuel cell works on the same principle as a battery but is continually fed with fuel. In one fuel cell, methanol (CH₃OH) enters on one side of the unit, and air enters on the other side. Both circulate past electrodes, and a chemical reaction occurs that produces electricity, plus carbon dioxide and water as byproducts. Which balanced chemical reaction equation best represents the reaction that occurs in this fuel cell?