95. Because atoms, molecules, and ions are very small, they are counted in units of moles, where 1 mole = 6.022 * 1023 molecules. Concentration of ions in a liquid is measured in units of moles per liter. The measure of the acidity of a liquid is called the pH of the liquid and is given by the formula

pH = - log (H),

where H is the concentration of hydrogen ions in units of moles per liter.

a. Water has a pH value of 7.0. How many hydrogen ions are in one liter of water?

There are 10⁻⁷ hydrogen ions in one-liter water

Step-by-step explanation:

Hi there!

a. If the pH = 7.0, then:

-log (H) = 7.0

multiply both sides of the equation by - 1

log (H) = - 7.0

Apply 10ˣ to both sides

10^ (log (H)) = 10⁻⁷

(H) = 10⁻⁷

There are 10⁻⁷ hydrogen ions in one-liter water.

Why 10^ (log (H)) = (H) ?

Let's consider this function:

y = 10^ (log x)

(Apply log to both sides)

log y = log 10^ (log x)

(Apply logarithmic property: log xᵃ = a · log x)

log y = log x · log 10

(log 10 = 1)

log y = log x

y = x

(since y = 10^ (log x) and y = x):

10^ (log x) = x

That's why 10^ (log (H)) = (H)