If 2 g of NaOH is dissolved to make 200 mL | vedclass

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Question

(A) The molarity $(M)$ is defined as the number of moles of solute per liter of solution. First, calculate the moles of $NaOH$: $n = \frac{	ext{mass}

Vedclass · Accepted Answer

$M < 0.25$

Vedclass · Answer

(A) The molarity $(M)$ is defined as the number of moles of solute per liter of solution. First, calculate the moles of $NaOH$: $n = \frac{	ext{mass}}{	ext{molar mass}} = \frac{2 \ g}{40 \ g/mol} = 0.05 \ mol$. At $25^{\circ} C$, the volume is $200 \ mL = 0.2 \ L$. Thus, the molarity at $25^{\circ} C$ is $M = \frac{0.05 \ mol}{0.2 \ L} = 0.25 \ M$. When the temperature increases to $90^{\circ} C$, the volume of the solution increases due to thermal expansion. Since the number of moles of $NaOH$ remains constant while the volume increases, the molarity $(M)$ will decrease. Therefore, the molarity at $90^{\circ} C$ will be less than $0.25 \ M$.

If $2 \ g$ of $NaOH$ is dissolved to make $200 \ mL$ solution at $25^{\circ} C$, the molarity $(M)$ at $90^{\circ} C$ is

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