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3 years ago

How many moles are in 29.8grams of CaCl2?

Chemistry

1 answer:

lora16 [44]3 years ago

4 0

Answer:

110.984 ?

i apologize if i'm wrong, you can report it if im wrong

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Explanation:

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How much potassium nitrate has to dissolve in water to absorb 105 kj of heat? there are 4.184 kj/kcal. also note the answer is t

joja [24]

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

Hydration energy of KNO3 = -155.5 kcal/mole

Heat of solution is the amount of heat absorbed by water when 1 mole of KNO3 is dissolved in it

Heat of solution = Hydration energy - Lattice energy

= -155.5 -(-163.8) = 8.3 kcal/mol

1 kcal/mol = 4.184 kJ/mole

Therefore, 8.3 kcal/mole = 4.184 * 8.3 = 34.73 kJ/mol

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

The given 105 kJ of heat would correspond to : 105/34.73 = 3.023 moles of KNO3

Molar mass of KNO3 = 101.1 g/mole

Mass of KNO3 = Molar mass * moles

= 101.1 * 3.023 = 305.63 g = 0.3056 kg

8 0

4 years ago

Pentaborane−9 (B5H9) is a colorless, highly reactive liquid that will burst into flames when exposed to oxygen. The reaction is

mote1985 [20]

Answer : The heat released per gram of the compound reacted with oxygen is 71.915 kJ/g

Explanation :

Enthalpy change : It is defined as the difference in enthalpies of all the product and the reactants each multiplied with their respective number of moles. It is represented as $\Delta H^o$

The equation used to calculate enthalpy change is of a reaction is:

$\Delta H^o_{rxn}=\sum [n\times \Delta H^o_f(product)]-\sum [n\times \Delta H^o_f(reactant)]$

The equilibrium reaction follows:

$2B_5H_9(l)+12O_2(g)\rightleftharpoons 5B_2O_3(s)+9H_2O(l)$

The equation for the enthalpy change of the above reaction is:

$\Delta H^o_{rxn}=[(n_{(B_2O_3)}\times \Delta H^o_f_{(B_2O_3)})+(n_{(H_2O)}\times \Delta H^o_f_{(H_2O)})]-[(n_{(B_5H_9)}\times \Delta H^o_f_{(B_5H_9)})+(n_{(O_2)}\times \Delta H^o_f_{(O_2)})]$

We are given:

$\Delta H^o_f_{(B_5H_9(l))}=73.2kJ/mol\\\Delta H^o_f_{(O_2(g))}=0kJ/mol\\\Delta H^o_f_{(B_2O_3(s))}=-1271.94kJ/mol\\\Delta H^o_f_{(H_2O(l))}=-285.83kJ/mol$

Putting values in above equation, we get:

$\Delta H^o_{rxn}=[(5\times -1271.94)+(9\times -285.83)]-[(2\times 73.2)+(12\times 0)]=-9078.57kJ/mol$

Now we have to calculate the heat released per gram of the compound reacted with oxygen.

From the reaction we conclude that,

As, 2 moles of compound released heat = -9078.57 kJ

So, 1 moles of compound released heat = $\frac{-9078.57}{2}=-4539.28kJ$

For per gram of compound:

Molar mass of $B_5H_9$ = 63.12 g/mole

$\Delta H^o_{rxn}=\frac{-4539.28}{63.12}=-71.915kJ/g$

Therefore, the heat released per gram of the compound reacted with oxygen is 71.915 kJ/g

7 0

3 years ago

A sample of a compound containing C, O, and silver (Ag) weighed 1.372 g. On analysis, it was found to contain 0.288 g O and 0.97

Sauron [17]

Answer:

The molecular formula for the compound is Ag₂C₂O₄, silver oxalate.

Explanation:

This is an easy excersise, we relate the moles of the elements in the compound with the molar mass of the total compound.

The sample weighs 1.372 g, with 0.288 g of O, 0.974 g of Ag and the rest, C

Therefore, 1.372g - 0.288 g - 0.974g = 0.112 g are C

We convert the mass to moles

0.288 g / 16g/mol = 0.018 moles of O

0.974 g / 107.87 g/mol = 0.00903 moles of Ag

0.112 g / 12 g/mol = 0.00933 moles of C

Now, the use of the molar mass of the compound. Let's prepare some rules of three:

1.372 g of compound contain 0.018 moles of O, 0.00903 moles of Ag and 0.00933 moles of C

Then, 308.8 g of compound (a mol) must contain:

(308.8 . 0.018) / 1.372 = 4 moles of O

(308.8 . 0.00903) / 1.372 = 2 moles of Ag

(308.8 . 0.00933) / 1.372 = 2 moles of C

The molecular formula for the compound is Ag₂C₂O₄, silver oxalate.

3 0

3 years ago

Read 2 more answers

a 5.og of sample of compound dissolve in enough water to form 100ml of a solution .this solution form osmotic pressure of 25 tor

storchak [24]

2889 tor plz believe

7 0

3 years ago

In photosynthesis, plants convert what type of energy into what other type of energy?

4vir4ik [10]

Answer:

Hope this helps!

Explanation:

Photosynthesis in plants converts solar energy into chemical energy using electrons and protons from water. The process of photosynthesis in plants involves a series of steps and reactions that use solar energy, water, and carbon dioxide to produce organic compounds and oxygen.

8 0

3 years ago