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makkiz [27]
2 years ago
15

Select all of the following equations that represent an exothermic reaction.

Chemistry
1 answer:
masya89 [10]2 years ago
6 0

Answer:

C(graphite) → C(diamond), ΔH = - 0.45 kcal

CH4 + 2O2 → CO2 + 2H2O + 212,800 cal

Explanation:

C(graphite) → C(diamond), ΔH = - 0.45 kcal

CH4 + 2O2 → CO2 + 2H2O + 212,800 cal

These reactions are exothermic reaction because heat is evolved.

The energy changes occur during the bonds formation and bonds breaking.

There are two types of reaction endothermic and exothermic reaction.

Endothermic reactions:

The type of reactions in which energy is absorbed are called endothermic reactions.

In this type of reaction energy needed to break the bond are higher than the energy released during bond formation.

For example:

C + H₂O   →  CO  + H₂

ΔH = +131 kj/mol

it can be written as,

C +  H₂O  + 131 kj/mol  →  CO  + H₂

Exothermic reaction:

The type of reactions in which energy is released are called exothermic reactions.

In this type of reaction energy needed to break the bonds are less than the energy released during the bond formation.

For example:

Chemical equation:

C + O₂   →  CO₂

ΔH = -393 Kj/mol

it can be written as,

C + O₂   →  CO₂ + 393 Kj/mol

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2 years ago
What is formed when water chemically combines with carbon dioxide
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When water chemically combines with carbon dioxide, a Carbonic acid is formed.

<u>Explanation</u>:

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3 years ago
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4 0
2 years ago
It has been proven that North America is moving west about 2 cm per year. How many kilometers wouldn’t move in 5000 years
Viefleur [7K]
0.1 km

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7 0
3 years ago
5. How much heat (in calories) is absorbed by a reaction when
Wewaii [24]

Answer:

1.2 × 10⁴ cal

Explanation:

Given data

  • Mass of water (m): 300 g
  • Initial temperature: 80 °C
  • Final temperature: 40°C

We can calculate the heat released by the water (Q_w) when it cools using the following expression.

Q_w = c \times m \times (T_f - T_i)

where

c is the specific heat capacity of water (1 cal/g.°C)

Q_w = \frac{1cal}{g.\°C}  \times 300g \times (40\°C - 80\°C) = -1.2 \times 10^{4} cal

According to the law of conservation of energy, the sum of the heat released by the water (Q_w) and the heat absorbed by the reaction (Q_r) is zero.

Q_w + Q_r = 0\\Q_r = -Q_w = 1.2 \times 10^{4} cal

7 0
2 years ago
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