The pH of a solution of hydrochloric acid is 1.67. What is the molarity of the acid?
Answer in units of mol/L
HCl is a strong acid, so it is 100 percent ionized.
pH=-log[H] but molarity is [H] because it is totally ionized, to
1.67=-log M
taking the antilog of each side
10^-1.67=M
M= 0.0234 moles/liter check the math.
To find the molarity of the hydrochloric acid solution, we need to use the definition of pH and the relationship between pH and molarity.
The definition of pH is given by the formula: pH = -log[H+], where [H+] represents the concentration of hydrogen ions in moles per liter (mol/L).
Given the pH value of the hydrochloric acid solution is 1.67, we can use this value to calculate the hydrogen ion concentration.
Step 1: Convert pH to [H+]
Using the pH formula, we have:
1.67 = -log[H+]
To isolate [H+], we need to remove the negative sign by multiplying both sides by -1:
-1.67 = log[H+]
Now, we need to convert from logarithmic form to exponential form:
10^-1.67 = [H+]
Step 2: Calculate [H+]
Using a calculator, evaluate 10^-1.67, which gives us:
[H+] ≈ 0.0206 mol/L
Step 3: Determine the molarity
The molarity (M) of a solution is defined as moles of solute per liter of solution. Since hydrochloric acid (HCl) is a strong acid, it completely dissociates in water, so we can assume that the concentration of hydrogen ions ([H+]) is equal to the concentration of HCl.
Therefore, the molarity (M) of the hydrochloric acid solution is approximately 0.0206 mol/L.