Review: Chemical vs Physical
Physical
The basic unit of all matter
Atom
How many hydrogen atoms: H20
2
The law of conservation of mass states that matter can neither be:_______ nor ________
Created nor destroyed
Is it a chemical or physical change: a car rusting
Chemical
Two or more atoms bonded together
Molecule
How many hydrogen atoms: 2H2O
4
Why must real chemical equations be balanced?
The law of conservation of mass; atoms cannot be created nor destroyed, only transferred
Which of the following is NOT a sign of a chemical reaction: a solid forming, a gas forming, a change in state of matter, color changing
A change in state of matter is a physical change (Remember: ice melting does not change its chemical composition)
Compound
What is the total number of atoms in a glucose molecule: C6H12O6
24 (6+12+6= 24)
Does the following equation obey the law of the conservation of mass? Explain why it does or does not.
Fe + Cl2 -> FeCl3
No, there is one too many Chlorine on the product side.
A beaker is filled with sodium hydroxide and placed on a scale Another liquid- copper sulfate- is inside the beaker but hanging over the liquid in a smaller glass. The copper sulfate is dropped into the sodium hydroxide, forming a solid piece of copper hydroxide in the beaker. What evidence is there that a chemical reaction has occurred?
Formation of a solid
The small number that shows the number of an atom
Subscript
Daily Double: How many atoms of sodium (Na):
2(NaOH)4
8
Does the following equation obey the law of the conservation of mass? Explain why it does or does not.
H2 + O2 --> H2O
No, there is one too many oxygen on the reactants side.
A beaker is filled with sodium hydroxide and placed on a scale Another liquid- copper sulfate- is inside the beaker but hanging over the liquid in a smaller glass. The mass on the scale is 60 g. The copper sulfate is dropped into the sodium hydroxide, forming a solid piece of copper hydroxide in the beaker. Will the mass of the beaker increase?
NO, the mass will stay the same. A chemical reaction has occurred, but mass was not created or destroyed.
Which side of the equation shows the reactants and which side shows the products?
Left: Reactants
Right: Products
How many atoms are there for EACH element: 2Ca3(PO4)2
Ca: 6
P: 4
O: 16
Hydrogen and Oxygen are diatomic, which means they cannot exist alone. They must always be bonded to another atom. Knowing this, how can you balance the following equation using coefficient(s):
H2 + O2 --> H2O
2H2 + 02 --> 2H20