Question

question 3 (1 point) how many grams of kbr do you need to make 0.2500 l of 1.21 m kbr solution? report your answer in grams but do not include units in your response. your answer: answer

Explanation:

Step1: Calculate moles of KBr

Use the formula $n = M\times V$, where $n$ is the number of moles, $M$ is molarity and $V$ is volume. Given $M = 1.21\ mol/L$ and $V=0.2500\ L$.
$n = 1.21\ mol/L\times0.2500\ L= 0.3025\ mol$

Step2: Calculate mass of KBr

The molar mass of KBr: $K$ has an atomic mass of approximately $39.1\ g/mol$ and $Br$ has an atomic mass of approximately $79.9\ g/mol$, so molar mass of $KBr$ is $39.1 + 79.9=119\ g/mol$. Use the formula $m=n\times M_m$, where $m$ is mass, $n$ is moles and $M_m$ is molar - mass.
$m = 0.3025\ mol\times119\ g/mol = 35.9975\approx36.0$

Answer:

36.0