Question

lab 4: q1
how many grams of nacl (molecular weight = 58.4 g mole-1) would you dissolve in water to make a total volume of 500 ml of solution to produce a 0.5 m solution of nacl? ______ g
type your numeric answer and submit
unanswered
lab 4: q2
how many grams of nacl (molecular weight = 58.4 g mole-1) would you dissolve in water to make a total volume of 500 ml of solution to produce a 50mm solution of nacl? ______ g
type your numeric answer and submit

Explanation:

Step1: Convert volume to liters

The volume $V = 500\ mL=0.5\ L$.

Step2: Calculate moles for the first - part

The molarity formula is $M=\frac{n}{V}$, where $M$ is molarity, $n$ is the number of moles, and $V$ is volume in liters. For a $0.5\ M$ solution with $V = 0.5\ L$, we can find the number of moles $n$ of $NaCl$. Rearranging the formula gives $n = M\times V$. So, $n_1=0.5\ mol/L\times0.5\ L = 0.25\ mol$.

Step3: Calculate mass for the first - part

The mass $m$ of a substance is given by $m=n\times MW$, where $MW$ is the molecular weight. Given $MW = 58.4\ g/mol$ and $n_1 = 0.25\ mol$, then $m_1=0.25\ mol\times58.4\ g/mol=14.6\ g$.

Step4: Convert millimolar to molar for the second - part

A $50\ mM$ solution means $M_2 = 50\times10^{- 3}\ mol/L=0.05\ mol/L$.

Step5: Calculate moles for the second - part

Using $n = M\times V$ with $M_2 = 0.05\ mol/L$ and $V = 0.5\ L$, we get $n_2=0.05\ mol/L\times0.5\ L = 0.025\ mol$.

Step6: Calculate mass for the second - part

Using $m=n\times MW$ with $MW = 58.4\ g/mol$ and $n_2 = 0.025\ mol$, then $m_2=0.025\ mol\times58.4\ g/mol = 1.46\ g$.

Answer:

For Lab 4: Q1: 14.6
For Lab 4: Q2: 1.46