Answer:
1.0 x 10⁻⁹ M OH⁻.
Explanation:
∵ [H₃O⁺][OH⁻] = 10⁻¹⁴.
[H₃O⁺] = 1.0 x 10⁻⁵ M.
∴ [OH⁻] = 10⁻¹⁴/[H₃O⁺] = 10⁻¹⁴/(1.0 x 10⁻⁵ M) = 1.0 x 10⁻⁹ M.
So, the right choice is: 1.0 x 10⁻⁹ M OH⁻.
Answer:
1.0 x 10-9M OH-
Explanation:
I just took the test and this was correct
When 21.45 g of KNO3 was dissolved in water in a calorimeter, the temperature fell from 25.00°C to 14.14 °C. If the heat capacity is 0.505KJ/°C, what will be the delta H for the solution process.
25.9 kJ/mol. (3 sig. fig. as in the heat capacity.)
ExplanationThe process:
[tex]\text{KNO}_3\;(s) \to \text{KNO}_3\;(aq)[/tex].
How many moles of this process?
Relative atomic mass from a modern periodic table:
K: 39.098;N: 14.007;O: 15.999.Molar mass of [tex]\text{KNO}_3[/tex]:
[tex]M(\text{KNO}_3) = 39.098 + 14.007 + 3\times 15.999 = 101.102\;\text{g}\cdot\text{mol}^{-1}[/tex].
Number of moles of the process = Number of moles of [tex]\text{KNO}_3[/tex] dissolved:
[tex]\displaystyle n = \frac{m}{M} = \frac{21.45}{101.102} = 0.212162\;\text{mol}[/tex].
What's the enthalpy change of this process?
[tex]Q = C\cdot \Delta T = 0.505 \times (25.00 - 14.14) = 5.4843\;\text{kJ}[/tex] for [tex]0.212162\;\text{mol}[/tex]. By convention, the enthalpy change [tex]\Delta H[/tex] measures the energy change for each mole of a process.
[tex]\displaystyle \Delta H = \frac{Q}{n} = \frac{5.4843\text{kJ}}{0.212162\;\text{mol}} = 25.8\;\text{kJ}\cdot\text{mol}^{-1}[/tex].
The heat capacity is the least accurate number in these calculation. It comes with three significant figures. As a result, round the final result to three significant figures. However, make sure you keep at least one additional figure to minimize the risk of rounding errors during the calculation.
To calculate the change in enthalpy for the solution process of KNO3, first find the heat transferred, q, through the formula q = m * C * ΔT. Then, calculate ΔH by dividing the heat transferred by the quantity of substance (in moles) involved, obtained from the given mass and the molar mass of KNO3.
Explanation:To calculate the change in enthalpy (ΔH) in the solution process of KNO3, you first need to figure out the amount of heat transferred during the process. This is done by using the formula: q = m * C * ΔT. In this case, the heat lost to the surrounding (q) equals the mass (m), which here is 21.45 g, times the specific heat capacity (C), which is given as 0.505 KJ/°C, times the change in temperature (ΔT), which is 25.00°C - 14.14°C.
After calculating q, ΔH can be calculated by taking into account the quantity of substance involved, which is the molar mass of KNO3. ΔH is reported in KJ/mol, so to get to ΔH, you'd find the molar mass of KNO3 (101.1 g/mol), figure out how many moles 21.45g represents, and then report the heat per mole. Therefore, the actual ΔH would depend on the specific values you use in these calculations.
Learn more about Change in Enthalpy here:https://brainly.com/question/32882904
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