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Coffee is a solution containing caffeine, acids, alkaloids, water, phenols, and many other chemicals. The solvent in the coffee solution is __________ and the rest of the chemicals dissolved in the solvent are called _________.

What is the difference between a saturated solution and a supersaturated solution?

12 eggs can be referred to as one dozen eggs.

______________ particles can be referred to as one mole of particles.

10 billion oxygen molecules (1 x 1010) is how many moles of molecular oxygen?

If the weights of carbon, hydrogen, and oxygen are approximately 12, 1, and 16 g/mol respectively, about how much would 1 mole of sucrose (C6H12O6) weigh?

The pH of a strong acid might be _____ while the pH of a strong base might be _____
The pH of pure water is _____.

What would be the pH of .002 moles of HNO3 dissolved in 2 L of water?

A base has a pH of 8.5. What is the concentration of OH- ions in the solution?

1 answer

  1. Coffee is a solution containing caffeine, acids, alkaloids, water, phenols, and many other chemicals. The solvent in the coffee solution is water, and the rest of the chemicals dissolved in the solvent are called solutes.

  2. A saturated solution is one in which no more solute can be dissolved at a given temperature, meaning it is in equilibrium with undissolved solute. A supersaturated solution is one that contains more solute than what can theoretically be dissolved at that temperature; it is in an unstable state that can lead to crystallization if disturbed.

  3. Avogadro's number particles can be referred to as one mole of particles.

  4. To find out how many moles of molecular oxygen are in 10 billion molecules of \(O_2\): \[ \text{Number of moles} = \frac{\text{Number of molecules}}{\text{Avogadro's number}} = \frac{10^{10}}{6.022 \times 10^{23}} \approx 1.66 \times 10^{-14} \text{ moles of } O_2 \]

  5. To calculate the weight of 1 mole of sucrose \(C_6H_{12}O_6\):

    • Carbon (C): \(6 \times 12 , \text{g/mol} = 72 , \text{g/mol}\)
    • Hydrogen (H): \(12 \times 1 , \text{g/mol} = 12 , \text{g/mol}\)
    • Oxygen (O): \(6 \times 16 , \text{g/mol} = 96 , \text{g/mol}\)

    Total weight of sucrose: \[ 72 + 12 + 96 = 180 , \text{g/mol} \] Thus, 1 mole of sucrose weighs 180 grams.

  6. The pH of a strong acid might be lower than 7 while the pH of a strong base might be greater than 7. The pH of pure water is 7.

  7. To find the pH of 0.002 moles of HNO3 dissolved in 2 L of water:

    • Concentration of \(HNO_3\): \[ \text{Concentration} = \frac{0.002 , \text{moles}}{2 , \text{L}} = 0.001 , \text{mol/L} \] Because HNO3 is a strong acid, it completely dissociates. Therefore, the concentration of \(H^+\) is also 0.001 mol/L. The pH is calculated as: \[ \text{pH} = -\log[H^+] = -\log(0.001) = 3 \]

  8. To find the concentration of \(OH^-\) ions in a solution with a pH of 8.5:

    • First, calculate the \(pOH\): \[ pOH = 14 - pH = 14 - 8.5 = 5.5 \]
    • Then, calculate the concentration of \(OH^-\): \[ [OH^-] = 10^{-pOH} = 10^{-5.5} \approx 3.16 \times 10^{-6} , \text{mol/L} \] Thus, the concentration of \(OH^-\) ions is approximately \(3.16 \times 10^{-6} , \text{mol/L}\).