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natita [175]
3 years ago
11

(b)

Chemistry
1 answer:
mixas84 [53]3 years ago
4 0

Answer:

Group 18th

Explanation:

The group 18th of periodic table which is composed of Noble gases mainly was missing from the Mendeleev's periodic table. The reason for this is that Noble gases are least reactive, therefore, it was difficult to predict such elements which do not react with other elements.

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A solution that is 0.20 m in hcho2 and 0.15 m in nacho2 find ph
Mashutka [201]
We are given
0.2 M HCHO2 which is formic acid, a weak acid
and
0.15 M NaCHO2 which is a salt which can be formed by reacting HCHO2 and NaOH

The mixture of the two results to a basic buffer solution
To get the pH of a base buffer, we use the formula
pH = 14 - pOH = 14 - (pKa - log [salt]/[base])

We need the pKa of HCO2
From, literature, pKa = 1.77 x 10^-4
Substituting into the equation
pH = 14 - (1.77 x 10^-4 - log 0.15/0.2)
pH = 13.87

So, the pH of the buffer solution is 13.87
A pH of greater than 7 indicates that the solution is basic and a pH close to 14 indicates high alkalinity. This is due to the buffering effect of the salt on the base.
5 0
3 years ago
A molecule made of hydrogen and carbon with Mr of 56 has the following composition: carbon 85.7%; hydrogen 14.3%. Calculate the
Veseljchak [2.6K]

Answer:

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vivado [14]
Yes, you can!




Hope this helped, and brainliest much needed and appreciated! Have a wonderful day!:)
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