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:
Option A = 2.2 L
Explanation:
Given data:
volume of one mole of gas = 22.4 L
Volume of 0.1 mole of gas at same condition = ?
Solution:
It is known that one mole of gas at STP occupy 22.4 L volume. The standard temperature is 273.15 K and standard pressure is 1 atm.
For 0.1 mole of methane.
0.1/1 × 22.4 = 2.24 L
0.1 mole of methane occupy 2.24 L volume.
H2(g) +C2H4(g)→C2H6(g)
H-H +H2C =CH2→H3C-Ch3
2C -H bonds and one C-C bond are formed while enthalpy change (dH) of the reaction,
H-H: 432kJ/mol
C=C: 614kJ/mol
C-C: 413 kJ/mol
C-C: 347 kJ/mol
dH is equal to sum of the energies released during the formation of new bonds or negative sign, and sum of energies required to break old bonds or positive sign.
The bond which breaks energy is positive.
432+614 =1046kJ/mol
Formation of bond energy is negative
2(413) + 347 = 1173 kJ/mol
dH reaction is -1173 + 1046 =-127kJ/mol
ANSWER: 23064 mg
EXPLANATION: To convert grams to milligrams, we multiply by 1000.
23.064 g x 1000 = 23064 mg
