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Dmitriy789 [7]
2 years ago
8

a chemist dissolved an 11.9-g sample of koh in 100.0 grams of water in a coffee cup calorimeter. when she did so, the water temp

erature increased by 26.0 ∘c. based on this, how much heat energy was required to dissolve the sample of koh? assume the specific heat of the solution is 4.184 j/g⋅°c.
Chemistry
1 answer:
Snowcat [4.5K]2 years ago
4 0

The heat of solution is -51.8 kJ/mol

<h3>What is the heat of solution?</h3>

We know that in a calorimeter, there is no loss or gain of energy. It is a good example of a closed system.

Number of moles of KOH =  11.9-g/56 g/mol = 0.21 moles

Temperature rise = 26.0 ∘c

Mass of the water = 100.0 grams

Heat capacity =  4.184 j/g⋅°c

Then;

ΔH = mcθ

ΔH = 100g * 4.184 j/g⋅°c * 26.0 ∘c = 10.88 kJ

Heat of solution = -(10.88 kJ/ 0.21 moles) = -51.8 kJ/mol

Learn more about heat of solution:brainly.com/question/24243878

#SPJ1

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Answer:

The decreasing order of first ionization energy: Se > Ge > In > Cs

The decreasing order of first ionization energy: x > y > z

Explanation:

Ionization energy refers to the energy needed to completely pull out an electron from the valence shell of a neutral gaseous atom.

First ionization energy is the energy involved in the removal of first valence electron.

<u><em>In the periodic table, down the group, as atomic radius of elements increases, the ionization energy decreases </em></u>

<u><em>Whereas, across a period, as atomic radius of elements decreases, the ionization energy increases.</em></u>

PART (A):

Position of the given elements in the periodic table:

Indium (In): Group 13, period 5

Germanium (Ge): Group 14, period 4

Selenium (Se): Group 16, period 4

Caesium (Cs): Group 1, period 6

Thus, the increasing order of atomic radius: Se < Ge < In < Cs

<u>Therefore, the decreasing order of first ionization energy: </u><u>Se > Ge > In > Cs</u>

PART (B):

Given elements:

element x: radius = 110 pm

element y: radius = 199 pm

element z: radius = 257 pm

Thus, the increasing order of atomic radius: x < y < z

<u>Therefore, the decreasing order of first ionization energy:</u><u> x > y > z</u>

5 0
3 years ago
If I had a mixture of salt, sand, and iron filings I could separate the mixture by …
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Okay to separate this mixture you will have to first use a magnet because the magnet will attract the iron filings out of the sand then you will remain with the sand and salt.

Next step is to add water to the sand and salt mixture the salt will dissolve in the water and the sand will not forming a heterogeneous mixture.Then using the method of filtration you can separate the sand from  the salt solution leaving the salt solution

 To separate the salt from the water use the method of evaporation this will enable you to get back the salt 

In the end you should beable to have the sand,salt and iron filings separate.

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3 years ago
MATCH UPS - PLEASE HELP ^^photo attachment
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Answer:

14. c

15. e

16. b

17. d

18. a

Explanation:

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3 years ago
How many moles of hydrogen are needed to produce 0.253 mol of water?
dmitriy555 [2]

using the equation of formation of water:

H2+O2---->H2O

Balancing the equation,

2H2+O2---->2H2O

So now use the ratio from the balance equation, we know that 2 mol of H2 are producing 2 mol of H2O so the ratio will be 1:1.

So as 2 mol of H2O are produced by 2 mol of H2.

That implies 1 mol of H2O are produced by 1 mol of H2.

That is 0.253 mol of H2O are produced by 0.253 mol of H2.

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