Question

Find about pH scale and state how exponents
are involved in the calculation of Ph(concentration of H* ion).​

Answer 1

Answer:

The pH Scale

Expressing the acidity of a solution by using the molarity of the hydrogen ion is cumbersome because the quantities are generally very small. Danish scientist Søren Sørenson (1868-1939) proposed an easier system for indicating the concentration of H + called the pH scale. The letters pH stand for the power of the hydrogen ion. The pH of a solution is the negative logarithm of the hydrogen-ion concentration.

pH = -log[H + ]

In pure water or a neutral solution the [H + ] = 1.0 × 10 -7 M. Substituting into the pH expression:

pH = -log[1.0 × 10 -7 ] = -(-7.00) = 7.00

The pH of pure water or any neutral solution is thus 7.00. For recording purposes, the numbers to the right of the decimal point in the pH value are the significant figures. Since 1.0 × 10 -7 has two significant figures, the pH can be reported as 7.00.

A logarithmic scale condenses the range of acidity to numbers that are easy to use. Consider a solution with [H + ] = 1.0 × 10 -4 M. That is a hydrogen-ion concentration that is 1000 times higher than the concentration in pure water. The pH of such a solution is 4.00, a difference of just 3 pH units. Notice that when the [H + ] is written in scientific notation and the coefficient is 1, the pH is simply the exponent with the sign changed. The pH of a solution with the [H + ] = 1 × 10 -2 M is 2 and the pH of a solution with the [H + ] = 1 × 10 -10 M is 10.

As we saw earlier, a solution with the [H + ] higher than 1.0 × 10 -7 is acidic, while a solution with the [H + ] lower than 1.0 × 10 -7 is basic. Consequently, solutions whose pH is less than 7 are acidic, while those with a pH higher than 7 are basic. Figure 1 illustrates this relationship, along with some examples of various solutions.

Answer 2

Information about pH scale:

• pH scale was developed by Lorensen in order to calculate the concentration and power of an acid or base.

• In pH scale , a log factor is used , because Lorensen found it easier to deal with logarithms which could make the concentration values much smaller and easier to handle.

• pH is expressed in the following manner:

$\boxed{ \bold{ \therefore \: pH = - log_{10} \bigg \{ {H}^{ + } \bigg \}}}$

• In other words, pH refers to the negative logarithm of the hydrogen ion concentration released from the acid upon dissociation in an aqueous medium.

Lets consider that [H+] concentration from a strong acid is 10^(-1) M:

So, pH will be calculated like this:

$\sf \therefore \: pH = - log_{10} \bigg \{ {H}^{ + } \bigg \}$

$\sf \implies \: pH = - log_{10} \bigg \{ {10}^{ - 1} \bigg \}$

$\sf \implies \: pH = - ( - 1)$

$\sf \implies \: pH = 1$

So, pH = 1.

• This is how exponents are handled in pH calculation.

Hope It Helps.