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# General Chemistry Problem Set

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Please refer to the attached file for the questions. I would like to get answers for all the red highlighted questions.

Part 1:
The mole provides a convenient package where we can make a connection between the mass of a substance and the number (count) of that substance. This is a familiar concept if you have ever bought nails at a hardware store, where you purchase nails by mass rather than count. Typically, there is a scale provided for weighing the nails. For example, a notice placed above the nail bin might read, "For the nails in the bin below, there are 500 nails per kg." Using this conversion factor, perform the following calculations.
• a. How many nails would you have if you had 0.15 kg?

• b. If you had 12 dozen nails, what would be their mass?

• c. What is the mass of one nail?

• d. What is the mass of 2.3 moles of nails?

Part 2:
The periodic table provides information about each element that serves somewhat the same purpose as the label on the nail bin described in Part 1, only in this case, the mass (molar mass) of each element is the number of grams of the element that contain 6.02 × 1023 atoms or molecules of the element. As you are aware, the quantity 6.02 × 1023
• a. If you had 0.15 kg of helium, how many helium atoms would you have?

• b. If you had 12 dozen helium atoms, what would be their mass?

• c. What is the mass of one helium atom?

• d. What is the mass of 1.5 moles of helium atoms?

Part 3:
Say there is a newly defined "package" called the binkle. One binkle is defined as being exactly 3 × 1012
• a. If you had 1.0 kg of nails and 1.0 kg of helium atoms, would you expect them to have the same number of binkles? Using complete sentences, explain your answer.

• b. If you had 3.5 binkles of nails and 3.5 binkles of helium atoms, which quantity would have more (count) and which would have more mass? Using complete sentences, explain your answers.

• c. Which would contain more atoms, 3.5 g of helium or 3.5 g of lithium? Using complete sentences, explain your answer.

3.18. Moles Within Moles and Molar Mass
Part 1

• a. How many hydrogen and oxygen atoms are present in 5 molecules of H2O?

• b. How many moles of hydrogen and oxygen atoms are present in 5 moles H2O?

• c. What are the masses of hydrogen and oxygen in 5.0 mole H2O?

• d. What is the mass of 1.0 mole H2O?

Part 2:
Two hypothetical ionic compounds are discovered with the chemical formulas XCl2 and YCl2, where X and Y represent symbols of the imaginary elements. Chemical analysis of the two compounds reveals that 0.25 mol XCl2 has a mass of 100.0 g and 0.50 mol YCl2has a mass of 125.0 g.
• a. What are the molar masses of XCl2 and YCl2?

• b. If you had 1.0-mol samples of XCl2 and YCl2, how would the number of chloride ions compare?

• c. If you had 1.0-mol samples of XCl2 and YCl2, how would the masses of elements X and Y compare?

• d. What is the mass of chloride ions present in 1.0 mol XCl2 and 1.0 mol YCl2?

• e. What are the molar masses of elements X and Y?

• f. How many moles of X ions and chloride ions would be present in a 200.0-g sample of XCl2?

• g. How many grams of Y ions would be present in a 250.0-g sample of YCl2?

• h. What would be the molar mass of the compound YBr3?
Part 3:
A minute sample of AlCl3 is analyzed for chlorine. The analysis reveals that there are 24 chloride ions present in the sample. How many aluminum ions must be present in the sample?
• a. What is the total mass of AlCl3 in this sample?

• b. How many moles of AlCl3 are in this sample?