Table of contents

1. Intro to General Chemistry3h 48m
2. Atoms & Elements4h 16m
3. Chemical Reactions4h 10m
4. BONUS: Lab Techniques and Procedures1h 38m
5. BONUS: Mathematical Operations and Functions48m
6. Chemical Quantities & Aqueous Reactions3h 53m
7. Gases3h 49m
8. Thermochemistry2h 37m
9. Quantum Mechanics2h 58m
10. Periodic Properties of the Elements3h 9m
11. Bonding & Molecular Structure3h 29m
12. Molecular Shapes & Valence Bond Theory1h 57m
13. Liquids, Solids & Intermolecular Forces2h 23m
14. Solutions3h 1m
15. Chemical Kinetics2h 53m
16. Chemical Equilibrium2h 29m
17. Acid and Base Equilibrium5h 1m
18. Aqueous Equilibrium4h 47m
19. Chemical Thermodynamics1h 50m
20. Electrochemistry2h 42m
21. Nuclear Chemistry2h 36m
22. Organic Chemistry5h 7m
23. Chemistry of the Nonmetals2h 39m
24. Transition Metals and Coordination Compounds3h 16m

6. Chemical Quantities & Aqueous Reactions

Dilutions

General Chemistry

6. Chemical Quantities & Aqueous Reactions

Dilutions

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Multiple Choice

A student prepared a stock solution by dissolving 15.0 g of KOH in enough water to make 150. mL of solution. She then took 15.0 mL of the stock solution and diluted it with enough water to make 65.0 mL of a final solution. What is the concentration of the final solution in mol/L?

0.450 mol/L

0.300 mol/L

0.154 mol/L

0.075 mol/L

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Verified step by step guidance

First, calculate the molar mass of KOH. Potassium (K) has a molar mass of approximately 39.10 g/mol, oxygen (O) is about 16.00 g/mol, and hydrogen (H) is about 1.01 g/mol. Add these values together to find the molar mass of KOH.

Next, determine the number of moles of KOH in the stock solution. Use the formula: \( \text{moles} = \frac{\text{mass}}{\text{molar mass}} \). Substitute the mass of KOH (15.0 g) and the molar mass calculated in the previous step.

Calculate the concentration of the stock solution in mol/L. Use the formula: \( \text{concentration} = \frac{\text{moles}}{\text{volume in liters}} \). Convert the volume of the stock solution from mL to L (150 mL = 0.150 L) and substitute the values.

Determine the moles of KOH in the 15.0 mL of stock solution that was taken for dilution. Use the concentration of the stock solution and the volume taken (15.0 mL = 0.015 L) to find the moles using: \( \text{moles} = \text{concentration} \times \text{volume} \).

Finally, calculate the concentration of the final solution. Use the formula: \( \text{concentration} = \frac{\text{moles}}{\text{volume in liters}} \). Convert the final solution volume from mL to L (65.0 mL = 0.065 L) and substitute the moles calculated in the previous step.