Look at the periodic table the element next at the right of Cl is the Ar and the atomic mass is 39.948 is bigger than the Cl 35.45. All the elements after that has mases bigger than Cl.

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3 years ago

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Determine the pH of 0.050 M HCN solution. HCN is a weak acid with a Ka equal to 4.9 x 10-10<br> DONE

nadezda [96]

Answer:

The pH of the solution is 5.31.

Explanation:

Let " $\alpha$ is the dissociation of weak acid - HCN.

The dissociation reaction of HCN is as follows.

$HCN+H_{2}O\rightarrow H_{3}O^{+}+CN^{-}$

Initial C 0 0

Equilibrium c(1- $\alpha$ ) c $\alpha$ c $\alpha$

Dissociation constant = $Ka= c\alpha \times \frac{c\alpha}{c(1-\alpha)}$

$=\frac{c\alpha^{2}}{(1-\alpha)}$

In this case weak acids $\alpha$ is very small so, (1- $\alpha$ ) is taken as 1.

$Ka=C\alpha^{2}$

$\alpha=\sqrt\frac{ka}{c}$

From the given the concentration = 0.050 M

Substitute the given value.

$\alpha=\sqrt\frac{4.9\times 10^{-10}}{0.05}=9.8\times 10^{-4}$

$[H_{3}O^{+}]=c\alpha$

$[H_{3}O^{+}]=0.05\times 9.8\times 10^{-4}= 4.9\times10^{-6}$

$pH= -log[H_{3}O^{+}]$

$=-log[4.9\times10^{-6}]$

$=6-log 4.9= 5.31$

Therefore, The pH of the solution is 5.31.

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3 years ago

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What is the molarity of a solution that contains 148g NaOH in 4.00 L solution? a 0.925 M b 0.0253 M c 0.459 M d 1.363 M

Anton [14]

Answer:

M = 0,925

Explanation:

n= mass/Molecular Weight

n = 148g / 39,99 (g/mol)

n= 3,7mol

M= n/Volumen(L)

M= 3,7mol/4L

M=0,925

8 0

3 years ago