Chemistry, 05.08.2019 19:10 camrenp9889

When 150. ml of 0.400 m h+ are mixed with 200. ml of 0.500 m oh-, the final temperature of the solution is 26.5°c. what was the initial temperature of the solution before the reaction occurred? assume that the solution has a total mass of 350. g and a specific heat capacity of 4.184 j/g°c. the enthalpy of neutralization for the reaction is -62.0 kj/mol of water produced.

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Answer from: densliverdensentos

Explanation:

The reaction between hydrogen ion and hydroxide ion will be as follows.

$H^{+} + OH^{-} \rightarrow H_{2}O$

so, ratio between hydrogen and hydroxide ions is 1 : 1.

Therefore, moles of $H^{+}$ = volume × concentration of $H^{+}$

= $150 mL \times frac{1 L}{1000 mL} \times 0.4 M$

= 0.06 mol

Similarly, moles of $OH^{-}$ = volume × concentration of $OH^{-}$

= $200 mL \times frac{1 L}{1000 mL} \times 0.5 M$

= 0.1 mol

Therefore, ratio of moles of hydrogen and hydroxide ions is as follows.

0.06 : 0.1

= 0.6 : 1

As, hydroxide ions are present in excess so, hydrogen ions are the limiting reagent.

Hence, moles of water formed = moles of $H^{+}$ ions = 0.06 mol.

So, heat released = moles of $H_{2}O \times \Delta H_{neutralization}$

= 0.062 × 62.0 kJ/mol

= 3.72 kJ

= 3.72 × 1000 J

= 3720 J

Let T is the initial temperature. So,

Heat released = Heat absorbed by the solution

= $m \times C \times \Delta T$

3720 J = $350 g \times 4.184 j/g ^{0}C \times (26.5 - T)$

T = $24.0 ^{o}C$

Thus, we can conclude that initial temperature is $24.0 ^{o}C$ .

Answer from: Quest

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Answer from: Quest

the dissociation of nickel hydroxide is follows:

$ni(oh)_2 > ni^2^+ + 2 oh^-$

$ksp for no(oh)2 = 5.5 * 10^-^1^6$

$5.5 * 10^-^1^6 = s * (2 s)^2 = 4 s^3$

$s^3 = 137.5 * 10^-^1^8$

$s = 5.14 * 10^-^6 = [oh^-]$

the concentration of hydroxide ion is

$5.14 * 10^-^6 = [oh^-]$

the equilibrium constant value of nickel hydroxide is = 6.1 * 10^-^1^6 and thus equilibrium equation can be written as:

$k = [ ni^2^+] * [oh^-]^2$

$6.1 * 10^-^1^6 = [ ni^2] * [5.14 * 10^-^6]^2$

$[ ni^2^+] = 0.23 * 10^-^4 mol /l$

thus, concentration of ni is 0.23 * 10^-^4 mol /l

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When 150. ml of 0.400 m h+ are mixed with 200. ml of 0.500 m oh-, the final temperature of the solut...

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