Question 1

How many molecules of sucrose are in 0.5 00L of a 2.00 molar solution of sucrose?

Accepted Answer

To calculate the number of molecules of sucrose in the solution, we need to use the Avogadro's number which is 6.02 × 10²³.

First, we need to calculate the number of moles of sucrose in the solution:
moles of sucrose = molarity × volume in liters
moles of sucrose = 2.00 mol/L × 0.500 L
moles of sucrose = 1.00 mol

Now, we can calculate the number of molecules of sucrose:
number of molecules = moles of sucrose × Avogadro's number
number of molecules = 1.00 mol × 6.02 × 10²³
number of molecules = 6.02 × 10²³

Therefore, the answer is B: 6.02 × 10²³ molecules of sucrose in 0.500 L of a 2.00 molar solution.

Question 2

Which of the following solutions is the most concentrated?

Accepted Answer

Concentration is defined as the amount of solute per unit volume of solution. The solution in option A has the highest concentration of 3 molar (M), indicating it has the most solute per liter of solution compared to the other options.

Question 3

Many solvents expand to occupy greater volumes with increasing temperature. What happens to the concentration of a solution made with such a solvent as its temperature is increased?

Accepted Answer

As the volume of the solvent increases with temperature, the same amount of solute is now spread out in a larger volume, leading to a decrease in concentration. Concentration is defined as the amount of solute per unit volume of solution, so if the volume increases while the amount of solute remains constant, the concentration decreases.

Question 4

How many molecules of sucrose are in a 0.500 moles of sucrose?

Accepted Answer

The answer of How many molecules of sucrose are in...

Question 5

How many grams of sodium chloride are needed to make 15 L of a solution that has a concentration of 3.0 g per liter of solution?

Accepted Answer

To find the amount of sodium chloride needed, multiply the concentration (3.0 g/L) by the volume of the solution (15 L). This gives 3.0 g/L * 15 L = 45 g.

Question 6

If you need 3.01 × 10²³ molecules of sucrose, how many liters of a 4.00 molar solution would you need?

Accepted Answer

To find the solution volume, we need to use the formula:

moles of solute = concentration (in moles per liter) x volume (in liters)

We know that we need 3.01 × 10^23 molecules of sucrose. We can convert this to moles by dividing by Avogadro's number:

moles of sucrose = 3.01 × 10^23 / 6.022 × 10^23 = 0.500 moles

To calculate the volume of a 4.00 M solution containing 0.500 moles, we rearrange the formula:

volume (in liters) = moles of solute / concentration (in moles per liter)

volume = 0.500 moles / 4.00 moles per liter = 0.125 liters

So, the answer is A: 0.125 L.

Question 7

How are intermolecular forces and solubility related?

Accepted Answer

Solubility depends on the interaction between the solvent and solute molecules. In order for a solute to dissolve, the solvent must be able to overcome the intermolecular forces holding the solute together. For example, in polar solvents, the solvent molecules have dipole-dipole interactions that can break up ionic or polar solute molecules. On the other hand, nonpolar solvents can dissolve nonpolar solutes because the weak London dispersion forces in both the solvent and solute can interact. Therefore, the ability of the solvent to overcome the intermolecular forces in a solute determines its solubility.

Question 8

How many molecules of sucrose are in 0.500 L of a 1.00 molar solution of sucrose?

Accepted Answer

The answer of How many molecules of sucrose are in...

Question 9

What is the sum of the atomic masses of all the atoms in sucrose,  ?

Accepted Answer

To find the sum of atomic masses in sucrose, we need to multiply the atomic mass of each element by the number of atoms of that element in the molecular formula of sucrose and then add them up. The molecular formula of sucrose is C12H22O11. The atomic masses of C, H, and O are approximately 12, 1, and 16 respectively. Therefore, the sum of atomic masses in sucrose would be:

(12 x 12) + (1 x 22) + (16 x 11) = 144 + 22 + 176 = 342 amu.

Question 10

Does a plastic bottle of fresh water sink or float in the ocean? Why?

Accepted Answer

A plastic bottle of fresh water will float in the ocean because the fresh water has a lower density than seawater. The plastic bottle adds to the overall volume, but is not enough to increase the density of the entire system so that it sinks.

Question 11

The warming of a saturated solution of calcium carbonate, CaCO₃, produces ________.

Accepted Answer

Calcium carbonate is less soluble at higher temperatures, so when a saturated solution is warmed, the excess calcium carbonate will precipitate out of the solution, resulting in a solid precipitate.

Question 12

How many moles of sugar, C₁₂H₂₂O₁₁, are there in 200. grams?

Accepted Answer

The molecular formula for sugar (sucrose) is C12H22O11. To find the molar mass, we add up the atomic masses of all the atoms in the formula: (12*12.01) + (22*1.01) + (11*16.00) = 342.34 g/mol. To find the number of moles in 200 grams, we use the formula: moles = mass / molar mass = 200 g / 342.34 g/mol = 0.584 moles, which rounds to 0.585 moles.

Question 13

Which of the following best describes a two-molar sucrose solution?

Accepted Answer

A two-molar solution means that there are 2 moles of the solute (in this case, sucrose) dissolved in 1 liter of solution. So, option A is the correct answer as it describes a one liter solution containing 2 moles of sucrose.

Question 14

How many grams of sugar (sucrose) are there in 5.0 liters of sugar water that has a concentration of 0.50 grams per liter of solution?

Accepted Answer

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Question 15

A student is told to use 10.00 grams of sodium chloride to make an aqueous solution that has a concentration of 10.00 grams of sodium chloride per liter of solution. About how much water will she use in making this solution?

Accepted Answer

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Question 16

What is the molarity when water is added to 2 moles of sodium chloride to make 0.5 liter of solution?

Accepted Answer

Molarity is calculated by dividing the number of moles of solute by the volume of the solution in liters. Here, $ \frac{2 \text{ moles}}{0.5 \text{ liter}} = 4 \text{ M} $.

Question 17

How many moles of water are there in 100. grams of water?

Accepted Answer

The molar mass of water (H2O) is approximately 18 g/mol. To find the number of moles in 100 grams of water, divide the mass of the water by its molar mass: 100 g / 18 g/mol = 5.55 moles.

Question 18

If you need 10. moles of sucrose, how many liters of a 4.0 molar solution would you need?

Accepted Answer

To obtain 10 moles of sucrose from a 4.0 molar solution, you divide the moles needed (10 moles) by the concentration of the solution (4.0 M), which equals 2.5 liters.

Question 19

A sealed plastic bottle is filled with enough sand so that the bottle floats just beneath the surface in ocean water. Some sand is then removed and the bottle is then placed in some fresh water where it floats just beneath the surface. What is true about the amount of sand that was removed from the bottle?

Accepted Answer

The answer of A sealed plastic bottle is filled with...

Question 20

What is the molarity of 0.50 liters of a solution with five moles of sucrose in it?

Accepted Answer

Molarity is calculated as moles of solute divided by liters of solution. Here, it's 5 moles / 0.50 liters = 10 molar.

Quiz 7: How Molecules Mix