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4 years ago

Help me please thanks

Chemistry

1 answer:

Sav [38]4 years ago

4 0

Element? I'm quite not sure but...Hope this helps!

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A 0.020 M solution of niacin has a pH of 3.26. (a) What percentage of the acid is ionized in this solution

mariarad [96]

Answer: 2.75%

Explanation:

$pH=-log [H+]$

$3.26 = -log [H+]$

$[H+] = 5.495\times 10^{-4} M$

$HA\rightleftharpoons H^++A^-$

initial 0.020 0 0

eqm 0.020 -x x x

$K_a=\frac{[H+][A-]}{[HA]}$

$K_a=\frac{[x][x]}{[0.020-x]}$

$x=5.495\times 10^{-4}$

$K_a=\frac{[5.495\times 10^{-4}]^2}{[0.020-5.495\times 10^{-4}]}$

$K_a =1.553\times 10^{-5}$

percent dissociation = $\frac{[H^+_eqm]}{[Acid_{initial}]}\times 100$

percent dissociation= $\frac{5.495\times 10^{-4}}{0.020}\times 100$

Thus percent dissociation= 2.75 %

5 0

3 years ago

How many grams of O₂ are required to react completely with 14.6 g of Na to form sodium oxide, Na₂O?

Bad White [126]

The balanced chemical reaction is :

$O_2 + 4Na \ -> \ 2Na_2O$

Number of moles of Na, $n = \dfrac{14.6}{23} = 0.635 \ mol$ .

Now, from balance chemical reaction we can see that 1 mole of oxygen reacts with 4 moles of sodium.

So, number of moles of oxygen are :

$n = \dfrac{0.635}{4}\ mole$

So, amount of oxygen required is :

$m = \dfrac{0.635 \times 32}{4}\ gm\\\\m = 5.08 \ gm$

Therefore, 5.08 gram of oxygen will react with 14.6 gram of sodium.

7 0

3 years ago

Which group has the greatest number of valence electrons?

mylen [45]

Answer:

Noble gases

Explanation:

No need

7 0

3 years ago

A chermist weighs out 400.0 g of Ca How many moles of Ca is this?

ra1l [238]

Answer:

<h3>The answer is 0.1 mol</h3>

Explanation:

To find out the number of moles we use the formula

$n = \frac{m}{M} \\$

where

n is the number of moles

M is the molar mass

m is the mass of the substance

From the question

m = 400 g

M of Ca = 40 g/mol

We have

$n = \frac{40}{400} = \frac{1}{10} \\$

We have the final answer as

Hope this helps you

4 0

4 years ago

Hat type of mixture is chicken noodle soup?

Lera25 [3.4K]

Heterogeneous mixture. cause you can separate the noodles from soup

4 0

3 years ago