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3 years ago

Total number of electrons present in 1.8 grams of water is

Chemistry

1 answer:

Liono4ka [1.6K]3 years ago

5 0

1 mole of water = 18 grams (you can find this by finding mass of two hydrogen and one oxygen which is (1*2) + 16 = 18)

1.8 grams = 0.1 moles

1 H2O molecule has 10 electrons so 0.1 moles can be computed as:

(6.023*10^23)*(0.1)*10 = 6.023*10^23 electrons

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A buffer solution contains 0.496 M hydrocyanic acid and 0.399 M sodium cyanide . If 0.0461 moles of sodium hydroxide are added t

pochemuha

Answer : The pH of the solution is, 9.63

Explanation : Given,

The dissociation constant for HCN = $pK_a=9.31$

First we have to calculate the moles of HCN and NaCN.

$\text{Moles of HCN}=\text{Concentration of HCN}\times \text{Volume of solution}=0.496M\times 0.225L=0.1116mole$

and,

$\text{Moles of NaCN}=\text{Concentration of NaCN}\times \text{Volume of solution}=0.399M\times 0.225L=0.08978mole$

The balanced chemical reaction is:

$HCN+NaOH\rightarrow NaCN+H_2O$

Initial moles 0.1116 0.0461 0.08978

At eqm. (0.1116-0.0461) 0 (0.08978+0.0461)

0.0655 0.1359

Now we have to calculate the pH of the solution.

Using Henderson Hesselbach equation :

$pH=pK_a+\log \frac{[Salt]}{[Acid]}$

Now put all the given values in this expression, we get:

$pH=9.31+\log (\frac{0.1359}{0.0655})$

$pH=9.63$

Therefore, the pH of the solution is, 9.63

4 0

3 years ago

Long ago, living things were divided into two main groups: _________

solmaris [256]

Answer:

I think the answer is Prokaryote and Eukaryote

Explanation:

6 0

2 years ago

Help in my exam plzz now

swat32

Answer:

yes your answer is correct

I hope it helps mate

I will always help you understanding your assingments have a great day

#Captainpower:)

8 0

2 years ago

You need to prepare 100.0 mL of a pH 4.00 buffer solution using 0.100 M benzoic acid (p K a = 4.20 ) and 0.200 M sodium benzoate

bekas [8.4K]

Answer : The volume of sodium benzoate and benzoic acid solution mixed to prepare this buffer should be, 29.0 mL and 71 mL respectively.

Explanation :

Let the volume of sodium benzoate (salt) be, x

So, the volume of benzoic acid (acid) will be, (100 - x)

Using Henderson Hesselbach equation :

$pH=pK_a+\log \frac{[Salt]}{[Acid]}$

Now put all the given values in this expression, we get:

$4.00=4.20+\log \left(\frac{(\frac{0.200x}{100})}{(\frac{0.100(100-x)}{100})}\right)$

x = 29.0

The volume of sodium benzoate = x = 29.0 mL

The volume of benzoic acid (acid) = (100 - x) = (100 - 29.0) = 71 mL

Thus, the volume of sodium benzoate and benzoic acid solution mixed to prepare this buffer should be, 29.0 mL and 71 mL respectively.

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2 years ago

the energy transformation that occurs when a firework goes off is a chemical to thermal to light and sound. however, some of the

quester [9]

Answer:

false

Explanation:

energy can't be destroyed

7 0

2 years ago