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3 years ago

Select the correct answer.

Chemistry

1 answer:

adelina 88 [10]3 years ago

3 0

Answer:

OB. Energy transfer would occur between the copper bars and the surroundings.

Explanation:

We define an isolated system as a system in which there is neither exchange of material nor energy while an open system is one in which materials and energy can be exchanged with the environment.

Given an open system consisting of two copper bars at different temperatures, energy will not only be exchanged between the copper bars but also between the copper bars and the environment.

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If a 95.27 mL sample of acetic acid (HC2H3O2) is titrated to the equivalence point with 79.06 mL of 0.113 M KOH, what is the pH

KATRIN_1 [288]

Answer:

8.73

Explanation:

The concentration of acetic acid can be determined as follows:

$M_1V_1 = M_2V_2\\(KOH) = (CH_3COOH)$

$M_{KOH}=0.113 M\\V_{KOH}=79.06 mL$

$V_{CH_3COOH}=95.27 \\\\M_{CH_3COOH)=?????$

$M_{CH3COOH} = \frac{M_{KOH}*V_{KOH}}{V_{CH_3COOH}}$

$M_{CH3COOH} = \frac{0.113*79.06}{95.27}$

$M_{CH3COOH} = 0.094 M$

Moles of $CH_3COOH$ = $95.27* 10^{-3}* 0.094$

=0.0090 moles

Moles of $KOH = 79.06*10^{-3}*0.113$

= 0.0090 moles

The equation for the reaction can be expressed as :

$CH_3COOH$ $+$ $KOH$ -----> $CH_3COO^{-}K^+$ $+$ $H_2O$

Concentration of $CH_3COO^{-$ ion = $\frac{0.0090}{Total volume (L)}$

= $\frac{0.0090}{(95.27+79.06)} *1000$

= 0.052 M

Hydrolysis of $CH_3COO^{-$ ion:

$CH_3COO^{-$ $+$ $H_2O$ -----> $CH_3COOH$ $+$ $OH^-$

$K = \frac{K_w}{K_a} = \frac{x*x}{0.052-x}$

⇒ $\frac{10^{-14}}{1.82*10^{-5}}= \frac{x*x}{0.052-x}$

= $0.5494*10^{-9}= \frac{x*x}{0.052-x}$

As K is so less, then x appears to be a very infinitesimal small number

0.052-x ≅ x

$0.5494*10^{-9}= \frac{x^2}{0.052}$

$x^2 = 0.5494*10^{-9}*0.052$

$x^2 = 0.286*10^{-10$

$x = \sqrt{0.286*10^{-10$

$x =0.535*10^{-5}M$

$[OH] = x =0.535*10^{-5}$

$pOH = -log[OH^-]$

$pOH = -log[0.535*10^{-5}]$

$pOH = 5.27$

pH = 14 - pOH

pH = 14 - 5.27

pH = 8.73

Hence, the pH of the titration mixture = 8.73

8 0

3 years ago

If I use the dropper to add 10 mL of drink mix to 50 mL of water, what is the

Yuliya22 [10]

Answer:

16.7%

Explanation:

From the question given above, the following data were obtained:

Volume of drink mix = 10 mL

Volume of water = 50 mL

Percentage of drink mix =?

Next, we shall determine the total volume of the solution. This can be obtained as follow:

Volume of drink mix = 10 mL

Volume of water = 50 mL

Total volume of solution =?

Total volume of solution = (Volume of drink mix) + (Volume of water)

Total volume of solution = 10 + 50

Total volume of solution = 60 mL

Finally, we shall determine the percentage of the drink mix in the solution. This can be obtained as follow:

Volume of drink mix = 10 mL

Total volume of solution = 60 mL

Percentage of drink mix =?

Percentage of drink mix = Vol. of drink mix / total volume × 100

Percentage of drink mix = 10/60 × 100

Percentage of drink mix = 16.7%

4 0

3 years ago

Is the statement correct or incorrect? Explain. A) It is correct. The ashes weigh less than the original wood and this proves th

Vladimir79 [104]

The correct answer is D

According to the law of conservation of mass, mass can not be destroyed or lost, it can just be rearranged in space, turned into energy etc.

Therefore, in our of example the wood was burned and turned into ashes. Even though the ashes weight less than the original wood, some of the solid mass of the wood was converted to gas and energy, so the overall mass remained the same.

7 0

3 years ago

Read the statement and determine if you agree or disagree. Use evidence to support your answer.

victus00 [196]

The sun doesn't heat the air much directly because the radiation is all visible light, which isn't easily absorbed by gases in the atmosphere. So I would disagree

3 0

3 years ago

Uranus was the first planet to be discovered using a telescope. true or false

slava [35]

Sir William Herschel announced its discovery on 13 March 1781, expanding the known boundaries of the Solar System for the first time in history and making Uranus the first planet discovered with a telescope.

7 0

4 years ago

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