Physical Changes
Is it possible to reverse a physical change?
Yes
Write the electron configuration of Calcium numerically
2,8,8,2
What does a chemcial equation represent?
The summary of a chemical reaction.
H₂ + O₂ → H₂O
2H₂ + O₂ → 2H₂O
What is a physical change?
In a physical change, the substance still consists of the same particles but the substance looks different before and after the change.
Why is cooking an egg considered a chemical change and not a physcial change?
Change in colour, change in state (liquid to solid), smell released
What are the substances on the right side of a chemical equation called?
Products
Na + Cl₂ → NaCl
2Na + Cl₂ → 2NaCl
Which of the following is not a physical change?
a. boiling an egg
b. cutting an apple
c. painting mix
d. melting butter
a
Which of the following is not an example of a chemical change?
a. burning wood
b. dissolving salt in water
c. rusting
d. baking a cake
b
What are the substances on the left side of a chemical equation called?
reactants
Fe + O₂ → Fe₂O₃
4Fe + 3O₂ → 2Fe₂O₃
What are some indicators of identifying physical changes?
Change in shape, change in state (solid, liquid or gas), mixing two substances together.
What are some indicators of a chemcial change?
Smell, change in colour, gas or solid being produced, seeing light or a change in temperature.
Write the word equation for the reaction of hydrogen with oxygen to form water.
Hydrogen + Oxygen → Water
C₃H₈ + O₂ → CO₂ + H₂O
C₃H₈ + 5O₂ → 3CO₂ + 4H₂O
When liquid mercury is cooled to -38.8 degrees celsius, it solidifies.
Is this a physical or chemical change? What symbol does mercury have?
Physical change (change state)
Hg
For each pair, explain which is more reactive:
K or Li
Potassium is more reactive than lithium because it has a bigger atomic radius, thus, weaker nuclear attraction (easier to lose an electron)
When magnesium ribbon is heated in air, it reacts with oxygen to produce a bright white flame and forms a white powder. Write the word equation for this chemical reaction.
Magnesium + Oxygen gas → Magnesium oxide
Al + HCl → AlCl₃ + H₂
2Al + 6HCl → 2AlCl₃ + 3H₂