1. Calculate the H3O⁺ ion concentration in an aqueous solution with a pH of 2.25 at 25°C. 2. In a 0.3395 M solution of weak acid (HA), the pH is 2.37 at 25°C. Calculate pKa for HA at this temperature.
3. The Ka for the weak acid HA is 5.63 × 10^–6. Calculate the Kb for conjugate base A⁻ at 25°C.
4. If the H3O⁺ ion concentration in an aqueous solution at 25 °C is measured as 3.01 x 10^–9 M, what is the pH of the solution?
5. What is the pH of a 0.0979 M HNO3 solution?
6. If the H3O⁺ ion concentration in an aqueous solution at 25 °C has a value of 3.38 x 10^–10 M, what is the pOH of the solution?

answer : third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

explanation :

let us write down the given equations

equation 1 :

equation 2 :

equation 3 :

let us use hess's law to find out which 2 equations can be added to get the third equation.

let us reverse equation 2 and multiply it by 2. the new equation that we get is,

equation 4 :

let us add equation 1 & 4

the above equation is similar to equation 3 but has different value for dhrxn.

therefore third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

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explanation:

because it is