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vladimir1956 [14]
4 years ago
11

In a __________ change the identity of the substance is

Chemistry
1 answer:
galben [10]4 years ago
7 0

Answer:

physical - arrangement of molecules changes

chemical - identity changes

Explanation:

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Oxygen has a total of 8 electrons, does that satisfy the octet rule? Explain why or why not.
murzikaleks [220]

Answer:

No

Explanation:

The first 2 electrons are in the inner shell, and the other 6 are valence electrons. Oxygen needs 2 more electrons to fill its valence shell and satisfy the octet rule.

5 0
3 years ago
When a 0.235-g sample of benzoic acid is combusted in a bomb calorimeter, the temperature rises 1.643 ∘C . When a 0.275-g sample
andrew-mc [135]

Answer : The heat of combustion per mole of caffeine at constant volume is 76197.18 kJ/mole

Explanation :

First we have to calculate the specific heat calorimeter.

Formula used :

Q=m\times c\times \Delta T

where,

Q = heat of combustion of benzoic acid = 26.38 kJ/g = 26380 J/g

m = mass of benzoic acid = 0.235 g

c = specific heat of calorimeter = ?

\Delta T = change in temperature = 1.643^oC

Now put all the given value in the above formula, we get:

26380J/g=0.235g\times c\times 1.643^oC

c=68323.38J/^oC

Thus, the specific heat of calorimeter is 68323.38J/^oC

Now we have to calculate the heat of combustion of caffeine.

Formula used :

Q=c\times \Delta T

where,

Q = heat of combustion of caffeine = ?

c = specific heat of calorimeter = 68323.38J/^oC

\Delta T = change in temperature = 1.584^oC

Now put all the given value in the above formula, we get:

Q=68323.38J/^oC\times 1.584^oC

Q=108224.23J=108.2kJ

Now we have to calculate the moles of caffeine.

\text{Moles of caffeine}=\frac{\text{Mass of caffeine}}{\text{Molar mass of caffeine}}

Mass of caffeine = 0.275 g

Molar mass of caffeine = 194.19 g/mole

\text{Moles of caffeine}=\frac{0.275g}{194.19g/mole}=0.00142mol

Now we have to calculate the heat of combustion per mole of caffeine at constant volume.

\text{Heat of combustion per mole of caffeine}=\frac{108.2kJ}{0.00142mol}=76197.18kJ/mole

Therefore, the heat of combustion per mole of caffeine at constant volume is 76197.18 kJ/mole

4 0
3 years ago
HELP ASAP PLS. The melting of a glacier is an example of the interactions among which of Earth’s spheres?
e-lub [12.9K]

Answer:

d. hydrospher, asthenosphere, atmosphere

5 0
3 years ago
Read 2 more answers
What role does weathering have in shaping Earth’s surface?
erma4kov [3.2K]

The answer is C because material is worn away because of weathering>

8 0
3 years ago
Read 2 more answers
Given the equation 2mg(s) + o2(g) → 2mgo(s) + 72.3 kj, how much heat is involved in the production of 5.0 mol of mgo? question 2
Rudik [331]
The heat is involved   in the  production of 5.0 mol of MgO  is   180 Kj

               calculation

2 Mg (s)   +O2 → 2 MgO

From  the  equation  above two  moles    of MgO  is used  therefore   

72.3   is for   2   moles

that is   72.3  kj =  2moles
                  ?      = 5  moles 

by  cross  multiplication

= 72.3  kj × 5/2     = 180  Kj  
    

7 0
3 years ago
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