AP Chem Unit 01 Most Challenging Questions

Multiple Choice

A subclass of deodorants, called antiperspirants, prevents sweating itself, typically by blocking sweat glands. Aluminum nitrate, Al(NO₃)₃, is an example of one common antiperspirant. A typical stick of deodorant contains 0.00425kg of aluminum nitrate. The molar mass of aluminum nitrate is 213g/mol. How many nitrate ions are in a typical stick of deodorant?

• 1.20x10²² ions

• 3.60x10²² ions

• 5.45x10²⁰ ions

• 1.63x10²¹ ions

Multiple Choice

How many protons are in 3 mol of helium atoms?

• 2

• 6

• 2 x (6.02x10²³)

• 6 x (6.02x10²³)

Multiple Choice

How many grams of chromium, Cr, are in 24.0g of MgCr₂O₇? The molar mass of MgCr₂O₇ is 240. g/mol.

• 10.4g

• 5.20g

• 52.0g

• 104g

Multiple Choice

3 NaHCO₃(s) + H₃C₆H₅O₇(aq) → 3 CO₂(g) + 3 H₂O(l) + Na₃C₆H₅O₇(aq)

Citric acid can be neutralized by the addition of sodium hydrogen carbonate as shown in the equation above. If 14.0L of CO₂(g) is collected at STP, how many moles of CO₂(g) were collected?

• 0.625mol CO₂(g)

• 314mol CO₂(g)

• 14.0mol CO₂(g)

• 3.00mol CO₂(g)

Multiple Select

A sample of a solid labeled as NaCl may be impure. A student analyzes the sample and determines that it contains 56 percent chlorine by mass. Pure NaCl(s) contains 61 percent chlorine by mass. Which of the following statements is consistent with the data?

SELECT ALL THAT APPLY.

• The sample contains NaCl(s) and LiCl(s).

• The sample contains only NaCl(s).

• The sample contains NaCl(s) and NaI(s).

• The sample contains NaCl(s) and KCl(s)

Multiple Choice

A student generates 4.50mol of oxygen gas, O₂, in the lab. If the student determines that the oxygen gas occupies 51.2L and exerts a pressure of 1682mmHg of pressure, what temperature was the sample of gas?

• 307°C

• 33.9°C

• 232,939°C

• 233,212°C

Multiple Choice

A sample of a hydrated compound, XY₂ · n H₂O, is placed into a crucible and heated. The data table for this laboratory investigation is shown below. The molar mass of the anhydrous compound XY₂ is 80.1g/mol. Based on the results of this investigation, which of the following formulas best represents the identity of the hydrated compound?

• XY₂ · H₂O

• XY₂ · 2H₂O

• XY₂ · 3H₂O

• XY₂ · 4H₂O

Multiple Choice

A student determines 11.4 g of a gas is in a 8.00L container at 0°C and 1 atm. Which of the following is the mostly likely identity of the gas?

• O₂

• N₂

• H₂

• Ne

Multiple Choice

How many moles of each of the ions are in 100.0mL of 0.100M Na₃PO₄(aq)?

• 0.0300mol Na⁺

  0.0100mol PO₄^3-

• 0.0300mol Na⁺

  0.0300mol PO₄^3-

• 0.0100mol Na⁺

  0.0100mol PO₄^3-

• 0.100mol Na⁺

  0.100mol PO₄^3-

Multiple Choice

A substance is determined to be 24.27% carbon, 71.65% chlorine, and 4.07% hydrogen. What is its empirical formula?

• CClH₂

• C₂Cl₂H₄

• C₂Cl₂H

• C₄Cl₄H₂