Question

A titration is performed on a 25.0 mL sample of calcium hydroxide. A volume of

Answer 1

Answer:

$\boxed {\boxed {\sf 0.28 \ M}}$

Explanation:

Titration is a method used to determine the concentration of a substance. The  formula for this is:

$M_AV_A= M_BV_B$

Where M is the molarity of the acid or base and V is the volume of the acid or base.

We know that 46.0 milliliters of a 0.15 molar solution of nitric acid wereused in the titration. 25.0 milliliters of solution of calcium hydroxide of unknown molarity were also used.

$\bullet \ M_A= 0.15 \ M \\\bullet \ V_A= 46.0 \ mL\\\bullet \ V_B= 25.0 \ mL$

Substitute these known values into the formula.

$0.15 \ M * 46.0 \ mL= M_B * 25.0 \ mL$

We are solving for the molarity of the base, so we must isolate the variable $M_B$. It is being multiplied by 25.0 milliliters. The inverse operation of multiplication is division, so we divide both sides of the equation by 25.0 mL.

$\frac {0.15 \ M * 46.0 \ mL}{25.0 \ mL}= \frac{M_B * 25.0 \ mL}{25.0 \ mL}$

$\frac {0.15 \ M * 46.0 \ mL}{25.0 \ mL}= M_B$

The units of milliliters (mL) cancel.

$\frac {0.15 \ M * 46.0 }{25.0}=M_B$

$\frac {6.9}{25.0 } \ M =M_B$

$0.276 \ M = M_B$

The original measurements have 2 or 3 significant figures. We always round our answer to the least number of sig figs, which is 2. For the number we calculated, that is the hundredths place. The 6 in the thousandths place tells us to round the 7 up to an 8.

$0.28 \ M \approx M_B$

The concentration of calcium hydroxide is approximately 0.28 M.