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what is the approximate ph at the equivalence point of a weak acid-strong base titration if 25 ml of aqueous formic acid require

vivado [14]

Answer:

pH at equivalence point is 8.52

Explanation:

$HCOOH+NaOH\rightarrow HCOO^{-}Na^{+}+H_{2}O$

1 mol of HCOOH reacts with 1 mol of NaOH to produce 1 mol of $HCOO^{-}$

So, moles of NaOH used to reach equivalence point equal to number of moles $HCOO^{-}$ produced at equivalence point.

As density of water is 1g/mL, therefore molarity is equal to molality of an aqueous solution.

So, moles of $HCOO^{-}$ produced = $\frac{29.80\times 0.3567}{1000}moles=0.01063moles$

Total volume of solution at equivalence point = (25+29.80) mL = 54.80 mL

So, at equivalence point concentration of $HCOO^{-}$ = $\frac{0.01063\times 1000}{54.80}M=0.1940M$

At equivalence point, pH depends upon hydrolysis of $HCOO^{-}$ . So, we have to construct an ICE table.

$HCOO^{-}+H_{2}O\rightleftharpoons HCOOH+OH^{-}$

I: 0.1940 0 0

C: -x +x +x

E: 0.1940-x x x

So, $\frac{[HCOOH][OH^{-}]}{[HCOO^{-}]}=K_{b}(HCOO^{-})=\frac{10^{-14}}{Ka(HCOOH)}$

species inside third bracket represent equilibrium concentrations

So, $\frac{x^{2}}{0.1940-x}=5.56\times 10^{-11}$

or, $x^{2}+(5.56\times 10^{-11}\times x)-(1.079\times 10^{-11})=0$

So, $x=\frac{-(5.56\times 10^{-11})+\sqrt{(5.56\times 10^{-11})^{2}+(4\times 1.079\times 10^{-11})}}{2}$

So, $x=3.285\times 10^{-6}M$

So, $pH=14-pOH=14+log[OH^{-}]=14+logx=14+log(3.285\times 10^{-6})=8.52$

5 0

2 years ago

2.37 x 0.004 Sig Fig

NeTakaya

Answer:

The answer is 0.00948

Explanation:

5 0

2 years ago

Read 2 more answers

In breckenridge, colorado, the typical atmospheric pressure is 520. torr. what is the boiling point of water (hvap 40.7 kj/mol)

Art [367]

362.51 Kelvin ln (p1/p2) =( dH / R) (1/T2 - 1/T1) ln (760 Torr /520Torr) =( 40,700 Joules / 8.314 J molâ’1K-1)(1/T2 - 1/373K) ln (1.4615) =( 4895.35)(1/T2 - 0.002681) 0.37946 = 4895.35/T2 - (0.002681)(4895.35) 0.37946 = 4895.35/T2 - (13.124) 0.37946 + 13.124 = 4895.35/T2 13.5039 = 4895.35/T2 T2 = 4895.35 / 13.5039 T2 = 362.51 answer is 362.51 Kelvin - 273 answer is also 89.5 Celsius

4 0

3 years ago

In the ground-state electron configuration of fe3+, how many unpaired electrons are present? express your answer numerically as

Virty [35]

Answer:
Iron has 5 unpaired electrons in Fe⁺³ state.

Explanation:

Iron having atomic number 26 has following electronic configuration in neutral state.

Fe = 1s², 2s², 2p⁶, 3s², 3p⁶, 4s², 3d⁶

When Iron looses three electrons it attains +3 charge with following electronic configuration.

Fe⁺³ = 1s², 2s², 2p⁶, 3s², 3p⁶, 3d⁵

The five electrons in d-orbital exist in unpaired form as,

3(dz)¹, 3d(xz)¹, 3d(yz)¹, 3d(xy)¹, 3(dx²-y²)¹

3 0

3 years ago

How many grams of Cl are in 525g of CaCl2

Tema [17]

First we determine the moles CaCl2 present:

525g / (110.9g/mole) = 4.73 moles CaCl2 present

Based on stoichiometry, there are 2 moles of Cl for every mole of CaCl2:
(2moles Cl / 1mole CaCl2) x 4.73 moles CaCl2 = 9.47 moles Cl

Get the mass:
9.47moles Cl x 35.45g/mole = 335.64 g Cl

8 0

3 years ago

Help me plzz I need help ​

Help me plzz I need help