Exam 3: Stoichiometry: Mass, Formulas, and Reactions

A 10.00 g sample of a hydrocarbon (which is a compound that contains only carbon and hydrogen) was burned in oxygen, and the carbon dioxide and water produced were carefully collected and weighed. The mass of the carbon dioxide was 30.50 g, and the mass of the water was 14.98 g. What was the empirical formula of the hydrocarbon?

Combustion analysis of an organic compound to determine the percentages of carbon, hydrogen, and oxygen in the compound depends on which of the following assumptions?

Which statements regarding combustion analysis to determine percent composition are not correct? I. The mass of oxygen in the sample compound can be determined from the mass of carbon dioxide that is produced. II. If a compound contains an element other than carbon and hydrogen, combustion analysis cannot be used to determine its empirical formula. III. Combustion analysis data alone is not sufficient to determine the molecular formula with certainty. IV. If some CO is produced rather than all CO₂, then the empirical formula that is calculated will be too high in carbon.

In one analysis, the density of ozone in an air sample was found to be 5.00 *10^-8 mol/L. What is the density in molecules per liter?

Which substance listed below contains the most oxygen atoms?

How many hydrogen atoms are there in a 346 g sample of pure ammonia (NH₃)?

How many atoms of chlorine are there in 25.0 g of calcium chloride (CaCl₂)?

A copper ore consisting of 12.5% copper(II) sulfide, when heated and reacted with oxygen gas, produces copper(II) oxide and sulfur dioxide. If the reaction has a 90.0% yield, how many grams of copper(II) oxide are produced when 1.00 kg of the copper ore is processed?

What is the difference in the chemistry between photosynthesis and respiration?

How many atoms are there in one mole of water?

As a purchasing agent for a pharmaceutical company, you need to determine the amount of platinum that is needed per kilogram of cisplatin, which is an anticancer drug. The chemical formula for cisplatin is PtCl₂(NH₃)₂, and its molar mass is 301g/mol.

A bottle containing 1,665 g of sulfuric acid (H₂SO₄, 98.08 g/mol) was spilled in a laboratory. The emergency spill kit contained a full 2.0 kg bottle of sodium carbonate (105.99 g/mol). Is this enough sodium carbonate to neutralize the acid according to the following reaction? H₂SO₄(aq) + Na₂CO₃(s) $\rightarrow$ Na₂SO₄(aq) + CO₂(g) + H₂O(l)

The mass of water obtained in a combustion analysis of a 1.000 g sample of an organic compound containing carbon, hydrogen, and oxygen is 0.6662 g. What is the mass percent of hydrogen in the compound?

Which statement A-D regarding the terms mole and molar mass is not correct?

Which statement, A-D, regarding photosynthesis is not correct? In the process of photosynthesis __________

Socrates was killed by a dose of hemlock, which is a poisonous herb in the carrot family. In a combustion experiment, 50.05 mg of the poisonous compound in hemlock was burned in excess oxygen to give 140.8 mg of CO₂ and 54.2 mg of H₂O. In a second experiment, it was determined that the compound is composed of only carbon, hydrogen, and nitrogen and has a molar mass less than 200 g/mol. What is the molecular formula of the poisonous compound in hemlock? Respond with the sum of the C, N, and H atoms in this compound. For example, if the molecular formula were CNH₂, you would respond 4.

Yeast converts glucose into ethanol and carbon dioxide in a process called fermentation. The unbalanced reaction equation is given below. Write the balanced equation, and find the percent yield for the reaction if 150.0 g of glucose yields 75.0 mL of ethanol (d = 0.789 g/mL). C₆H₁₂O₆(aq) $\rightarrow$ C₂H₅OH(aq) + CO₂(g)

Some indoor air purification systems work by converting some of the oxygen in the air to ozone. The ozone oxidizes mold, mildew spores, and other biological pollutants. It is claimed that one such system generates 5.0 g of ozone per hour by passing dry air through the purifier at a rate of 5.0 L/min. If 1.0 L of air contains 0.28 g of oxygen, what percent of the O₂ molecules are converted to O₃ molecules?

A sample of water (H₂O) contains 1.81 * 10²⁴ molecules. How many moles of atoms are there in this sample?

Carbon monoxide is used in refining iron ore to produce the metal. Assuming the reaction yield is 100%, how many grams of iron would be produced if 5.00 mol of carbon monoxide were exposed to 800 g iron(III) oxide? Fe₂O₃(s) + 3CO(g) $\rightarrow$ 2Fe(s) + 3CO₂(g)