Burning, cooking
Explanation:
Chemical changes that happens in school are:
Cooking of meals
Burning of wastes
Chemical reactions in laboratories
Rusting of iron used in construction
- A chemical change is a change that produces new kinds of substances.
- These changes are usually accompanied by energy and mass changes.
- Most of such changes are not reversible.
Chemical changes are driven by change in chemical properties of matter.
In a school, iron components might begin to rust. This is a chemical change.
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Answer:
<h2><u><em>100 kcal of bond energy</em></u></h2>
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Given:
<span> 2.1 moles of chlorine gas (Cl2) at standard temperature and pressure (STP)
Required:
volume of CL2
Solution:
Use the ideal gas law
PV = nRT
V = nRT/P
V = (2.1 moles Cl2) (0.08203 L - atm / mol - K) (273K) / (1 atm)
V = 47 L</span>
<span>Charles' law says "at a constant pressure, the volume of a fixed amount of gas is directly proportional to its absolute temperature".
V </span>α T
Where V is the volume and T is the temperature in Kelvin of the gas. We can use this for two situations as,
V₁/T₁ = V₂/T₂
V₁ = 2.00 L
T₁ = 40.0 ⁰C = 313 K
V₂ = ?
T₂ = 30.0 ⁰C = 303 K
By applying the formula,
2.00 L / 313 K = V₂ / 303 K
V₂ = (2.00 L / 313 K) x 303 K
V₂ = 1.94 L
Hence, the volume of the balloon at 30.0 ⁰C is 1.94 L
22.4 molecules are in 4.48 liters of CO 2
