When a 16.3 mL sample of a 0.382 M aqueous hydrofluoric acid solution is titrated with a 0.478 M aqueous sodium hydroxide solution, what is the pH at the midpoint in the titration

3.25  

Explanation:

We don't have to do calculations with volumes and concentrations.

We just have to remember that, at the midpoint in the titration of a weak acid by a strong base,

pH = pKₐ

For formic acid,

pKₐ = 3.25, so, at the midpoint,

pH = 3.25

The first graph below shows the titration curve for your acid. The endpoint is at about 13 mL, so the midpoint is at 6.5 mL, and the pH is about 3.2.

In the second graph, the concentration of formic acid has increased by 50% to 0.573 mol·L⁻¹, so the endpoint has moved to about 19.5 mL and the midpoint is around 9.8 mL. However, the pH at the midpoint is still about 3.2.

This shows that the pH at the midpoint depends only on the pKₐ of the acid.

the equation that correctly represent the reaction for formation of ammonia is

n2+ 3h2 → 2nh3 (answer d)

1 mole of nitrogen gas (n2) react with 3 moles of hydrogen gas (h2) to form 2 moles of ammonia ( nh3). this is in a process known as haber process were iron is used as a catalyst and reaction take place that a higher temperature and pressure. the process is exothermic hence energy is released.

because natural gas is colorless, odorless, and tasteless, distributors add mercaptan (a chemical that smells like sulfur) to give natural gas a distinct unpleasant odor (it smells like rotten eggs). they locate the types of rock that are likely to contain natural gas deposits.