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Olin [163]
3 years ago
10

Early people observed their surroundings and relied on...

Chemistry
2 answers:
Damm [24]3 years ago
6 0
Either instinct or observation
PolarNik [594]3 years ago
4 0
Each Other and the sun but now a days we relied on our phones
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Which of the following can be true about a chemical reaction
MissTica
chemical reactions can release heat (a)
3 0
3 years ago
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
The table shows the charge on three unknown subatomic particles.
brilliants [131]

Answer:

B. only particle Z

Explanation:

In the case of subatomic particles, those positive and neutral are located in the nucleus, and those with a negative charge on the outside.

8 0
3 years ago
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What happens to the particles of a substance when thermal energy is added to the substance?
Sergio039 [100]
The answer is B) particles move faster.
8 0
3 years ago
In dry climates, people often dig wells to find additional sources of water
vekshin1

Answer:

D i think, sorry if its wrong

Explanation:

3 0
2 years ago
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