1)How many joules are needed to heat 8.50 grams of ice from -10.0 degrees to 25.0 degrees?
2)Calculate the hydronium ion concentration and the hydroxide ion concentration in blood, the pH of which is 7.3(slightly alkaline)
heat to move T of ice from -10 to zero is
q1 = mass x specific heat ice x delta T.
mass is 8.5 g, you can look up the specific heat of ice, and delta T is 0 -(-10) = 10.
Next we must melt the ice.
q2 = mass x heat fusion of ice.
Next we must move T of ice at 0 degrees C to 25 degrees C.
q3 = mass x specific heat water x delta T.
Total is q1 + q2 + q3.
1) To calculate the amount of energy needed to heat a substance, we can use the equation: q = mcΔT, where q is the heat energy, m is the mass, c is the specific heat capacity, and ΔT is the change in temperature.
First, we need to determine the heat energy required to raise the temperature of the ice from -10.0 degrees to 0 degrees. The specific heat capacity of ice is 2.09 J/g°C.
q₁ = mcΔT
q₁ = 8.50 g * 2.09 J/g°C * (0 - (-10.0) °C)
q₁ = 178.85 J
Next, we need to calculate the heat energy required to melt the ice into water. The heat of fusion for ice is 334 J/g.
q₂ = mΔH
q₂ = 8.50 g * 334 J/g
q₂ = 2839 J
Finally, we calculate the heat energy required to raise the temperature of the water from 0 degrees to 25.0 degrees. The specific heat capacity of water is 4.18 J/g°C.
q₃ = mcΔT
q₃ = 8.50 g * 4.18 J/g°C * (25.0 - 0) °C
q₃ = 892.15 J
The total amount of energy needed is the sum of q₁, q₂, and q₃:
Total energy = q₁ + q₂ + q₃
Total energy = 178.85 J + 2839 J + 892.15 J
Total energy = 3910 J
Therefore, 3910 joules are needed to heat 8.50 grams of ice from -10.0 degrees to 25.0 degrees.
2) The pH of 7.3 indicates that the blood is slightly alkaline, which means that it has more hydroxide ions (OH-) than hydronium ions (H3O+).
To calculate the hydronium ion concentration and hydroxide ion concentration in blood, we can use the pH equation: pH = -log[H3O+], where [H3O+] represents the concentration of hydronium ions in moles per liter (M).
For a pH of 7.3, we can calculate the hydronium ion concentration as follows:
pH = -log[H3O+]
7.3 = -log[H3O+]
To find the concentration [H3O+], we need to take the antilogarithm (10^x) of both sides:
10^7.3 = [H3O+]
Calculating this, we find that the hydronium ion concentration in blood is approximately 5.01 x 10^(-8) M.
Since water is neutral, the concentration of hydroxide ions (OH-) is equal to the concentration of hydronium ions:
[OH-] = [H3O+] = 5.01 x 10^(-8) M
Therefore, the hydronium ion concentration and the hydroxide ion concentration in the blood, which has a pH of 7.3, are approximately 5.01 x 10^(-8) M.