The pKa of phenol is 10.00, determine the Ka to two significant figures.
pKa = -log Ka.
10.00 = -log Ka
-10.00 = log Ka
Ka = 1E-10
The pKa is the negative logarithm (base 10) of the acid dissociation constant (Ka).
To determine the Ka from the given pKa, we can use the formula:
Ka = 10^(-pKa)
Substituting the given pKa value of 10.00 into the formula:
Ka = 10^(-10.00)
Calculating this equation:
Ka = 1 x 10^(-10)
So, the Ka of phenol is approximately 1 x 10^(-10), which can be rounded to 1.0 x 10^(-10) to two significant figures.
To determine the Ka (acid dissociation constant) of phenol, we need to use the pKa value, which is defined as the negative logarithm (base 10) of the Ka. In this case, the pKa of phenol is given as 10.00.
To find the Ka, we need to take the antilogarithm (inverse logarithm) of the negative pKa value. The antilogarithm of -pKa is equal to 10 raised to the power of -pKa.
Therefore, to find the Ka:
Ka = 10^(-pKa)
Substituting the given pKa value of 10.00 into the equation:
Ka = 10^(-10.00)
To evaluate this expression, we can use a scientific calculator or an online calculator that supports exponents and negative numbers.
Let's calculate the value using a calculator:
Ka = 0.0000000001
Round this value to two significant figures according to the number of significant figures in the pKa value:
Ka ≈ 1.0 x 10^-10
Therefore, the Ka of phenol to two significant figures is approximately 1.0 x 10^-10.