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kirza4 [7]
3 years ago
15

Pls answer it will be really helpful

Chemistry
2 answers:
IRISSAK [1]3 years ago
4 0

Answer:

304 because 76% - 400 is 96, subtract 400 by 96

vlabodo [156]3 years ago
3 0
It’s 96 I believe? Sorry if I’m wrong
You might be interested in
Calculate the ratio of naf to hf required to create a buffer with ph = 4.05.
NARA [144]
PH is the test of acidity or basicity of a solution. it follows the formula: 
pH = pKa + log [salt] / [acid] where NaF is the salt and HF is the acid in this case. 

By literature, Ka of HF is 3.5*10^-4 
<span>pKa= -log(Ka)=</span><span> 3.46 </span>

<span>pH = pKa + log [NaF / [HF] </span>

4.05 = 3.46 + log [NaF / [HF] 

log [NaF / [HF]<span> = 0.59
</span>
[NaF / [HF] = 3.89
4 0
3 years ago
Read 2 more answers
several kinds of bears are found on earth. most bears are brown or black, but one type of bear, the polar bear is white. What pr
LekaFEV [45]

Explanation:

they are white so they can camouflage, but actually the polar bears skin is black and it's hair is hollow

4 0
3 years ago
Read 2 more answers
Potassium nitrate has a lattice energy of -163.8 kcal/mol and a heat of hydration of -155.5 kcal/mol.
Brut [27]

Answer:

<em>293.99 g </em>

OR

<em>0.293 Kg</em>

Explanation:

Given data:

Lattice energy of Potassium nitrate (KNO3) = -163.8 kcal/mol

Heat of hydration of KNO3 = -155.5 kcal/mol

Heat to absorb by KNO3 = 101kJ

To find:

Mass of KNO3 to dissolve in water = ?

Solution:

Heat of solution = Hydration energy - Lattice energy

                           = -155.5 -(-163.8)

                           = 8.3 kcal/mol

We already know,

1 kcal/mol = 4.184 kJ/mole

Therefore,

= 4.184 kJ/mol x 8.3 kcal/mol

= 34.73 kJ/mol

Now, 34.73 kJ of heat is absorbed when 1 mole of KNO3 is dissolved in water.

For 101 kJ of heat would be

= 101/34.73

= 2.908 moles of KNO3

Molar mass of KNO3 = 101.1 g/mole

Mass of KNO3 = Molar mass x moles

                         = 101.1 g/mole  x  2.908

                         = 293.99 g

                         = 0.293 kg

<em><u>293.99 g potassium nitrate has to dissolve in water to absorb 101 kJ of heat. </u></em>     

4 0
3 years ago
Neutralizing an olympic size swimming pool is conceptually very similar to performaing a massive titration experiment. Suppose a
MrRissso [65]

Answer:

6,97x10⁻³ gallons

Explanation:

pH is defined as:

pH = -log [H⁺]

Thus, you need to have, in the end:

10⁻⁷ = [H⁺]

And you have, in the first:

10^{-9,33} = [H⁺]

The volume of swimming pool is:

700'000 galllons ×\frac{3,78541 L}{1 gallon} = 2649787 L

Thus, the moles of H⁺ in the first and in the end are:

First:

10^{-9,33}mol/L × 2649787L = 1,24x10⁻³ moles

End:

10^{-7}mol/L × 2649787L = 0,265 moles

Thus, the moles of H⁺ you need to add are:

0,265 - 1,24x10⁻³ = <em>0,26376 moles</em>

These moles comes from 10M HCl, thus, the volume in gallons you need to add are:

0,26376moles*\frac{1L}{10moles}* \frac{1gallon}{3,78541L} =

<em>6,97x10⁻³ gallons</em>

<em></em>

I hope it helps!

7 0
3 years ago
Ion<br> If we add an electron to a stable element we call it a(n)_____ion<br><br> anion<br> cation
masha68 [24]
The answer is a cation, I may be wrong but cation is plus and anion is subtract
3 0
3 years ago
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