What is the Correct Value of Kw at 10°C?

In summary, the concentration of OH in 1 M of HCl at 10°C can be calculated using the equilibrium constant, Kw=KaKb, and the dissociation of HCl. The value of Kw at 10°C is 10^-14 and the resulting concentration of OH is 3x10^-15, according to the table provided. This may differ from the expected value of 1x10^-14, but the discrepancy may be due to the MCAT's specific calculations.
  • #1
brake4country
216
7

Homework Statement


At 10 C, the concentration of OH in 1 M of HCl is approximately:

Answer: 3x10^15

Homework Equations


Kw=KaKb

The Attempt at a Solution


This answer throws me off. If we assume that HCl completely dissociates, we use the [H+] from the acid in the above equation:
1x10^-14 = 1 [OH]

I get 1 x 10^-14, not 3 x 10^-15. What am I missing here? Is my book wrong? Thanks.
 
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  • #3
Thanks for the table but I still don't think I get it. Since this is for the mcat, how am I supposed to calculate the OH concentration at 10 C?
 
  • #4
What is the definition of Kw?
 
  • #5
Kw is the equilibrium constant for [H+] and [OH-]. In aqueous solution, Kw remains at 10^-14.
 
  • #6
brake4country said:
In aqueous solution, Kw remains at 10^-14.

Have you really seen the table? What is the Kw value at 10°C?
 

Related to What is the Correct Value of Kw at 10°C?

1. What is the relationship between the concentration of OH in HCl and the strength of the acid?

The concentration of OH in HCl is inversely proportional to the strength of the acid. This means that as the concentration of OH increases, the strength of the acid decreases. This is because HCl is a strong acid that dissociates completely in water, leaving very few OH ions.

2. How does the concentration of HCl affect the concentration of OH?

The concentration of HCl has a direct effect on the concentration of OH ions. This is because HCl ionizes in water to produce H+ and Cl- ions. Since H+ and OH- ions are constantly reacting to form water molecules, an increase in H+ ions will decrease the concentration of OH- ions and vice versa.

3. How can the concentration of OH in HCl be determined experimentally?

The concentration of OH in HCl can be determined experimentally using a titration method. A known volume of the HCl solution is titrated with a base, such as NaOH, until the equivalence point is reached. At this point, the moles of HCl can be calculated, and since HCl completely dissociates into H+ and Cl- ions, the concentration of OH can be calculated.

4. What is the relationship between the concentration of OH in HCl and the pH of the solution?

The concentration of OH in HCl is inversely related to the pH of the solution. As the concentration of OH increases, the pH of the solution becomes more basic (higher pH) due to the decrease in H+ ions. Conversely, a decrease in OH concentration leads to a decrease in pH (more acidic).

5. How does temperature affect the concentration of OH in HCl?

Temperature has a minimal effect on the concentration of OH in HCl. However, as the temperature increases, the dissociation of HCl into H+ and Cl- ions becomes more favorable, leading to a slight increase in the concentration of OH ions. This is because higher temperatures provide more energy for the molecules to overcome the bond between H+ and Cl- ions.

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