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3 years ago

25. The periodic table is based on an element's A. atomic number. B. molecular size. C. molecular mass. D. atomic mass.

Chemistry

2 answers:

VashaNatasha [74]3 years ago

8 0

It is arranged by Atomic Number

miskamm [114]3 years ago

3 0

Im pretty sure the answer is a:atomic number

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A chemist titrates 220.0 mL of a 0.1917M propionic acid (HC2H5CO2) solution with 0.1787 M KOH solution at 25Â°C. Calculate the p

natima [27]

Answer : The pH at equivalence is, 9.08

Explanation : Given,

Concentration of $HC_2H_5CO_2$ = 0.1917 M

Volume of $HC_2H_5CO_2$ = 220.0 mL = 0.220 L (1 L = 1000 mL)

First we have to calculate the moles of $HC_2H_5CO_2$

$\text{Moles of }HC_2H_5CO_2=\text{Concentration of }HC_2H_5CO_2\times \text{Volume of }HC_2H_5CO_2$

$\text{Moles of }HC_2H_5CO_2=0.1917M\times 0.220L=0.0422$

As we known that at equivalent point, the moles of $HC_2H_5CO_2$ and KOH are equal.

So, Moles of KOH = Moles of $HC_2H_5CO_2$ = 0.0422 mol

Now we have to calculate the volume of KOH.

$\text{Volume of }KOH=\frac{\text{Moles of }KOH}{\text{Concentration of }KOH}$

$\text{Volume of }KOH=\frac{0.0422mol}{0.1787M}$

$\text{Volume of }KOH=0.00754$

Total volume of solution = 0.220 L + 0.00754 L = 0.22754 L

Now we have to calculate the concentration of KCN.

The balanced equilibrium reaction will be:

$HC_2H_5CO_2+KOH\rightleftharpoons C_2H_5CO_2K+H_2O$

Moles of $C_2H_5CO_2K$ = 0.0422 mol

$\text{Concentration of }C_2H_5CO_2K=\frac{0.0422mol}{0.22754L}=0.1855M$

At equivalent point,

$pH=\frac{1}{2}[pK_w+pK_a+\log C]$

Given:

$pK_w=14\\\\pK_a=4.89\\\\C=0.1855M$

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

$pH=\frac{1}{2}[14+4.89+\log (0.1855)]$

$pH=9.08$

Therefore, the pH at equivalence is, 9.08

6 0

3 years ago

True or false: Soils are formed from the breakdown of rock below them. This rock material is referred to as "parent material."

Nookie1986 [14]

False

The soil is formed from the erosion of surface rocks, not rocks below the soil.

I hope this helps!

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4 years ago

How do i describe how a constant volume calorimeter can be used to measure the heat transferred from a burning piece of coal to

zepelin [54]

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3 years ago

If the molar mass of the compound in problem 3 is 73.8 grams/mole? what is the molecular formula ?

umka21 [38]

The molecular formula would be Li2CO3

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3 years ago

Find 6 examples of where chemistry and agriculture work together

Alina [70]

Answer:

Chemistry deals with compounds, both organic and inorganic, and agriculture deals with the production of organic products using both organic and inorganic inputs Thus Chemistry forms an integral part of agriculture from molecular to organ level.

Explanation:

i hope this helps you! Have a nice day <33

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4 years ago

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