It's a physical change because the composition of the salt hasn't change. Only the change in substance/form has occured. To tell if something has undergone physical change is:
• Melting
• Boiling
• Freezing
• Condensing
• Breaking
• Bending
• Dissolving
• Molecules can change motion and proximity
To tell if something changed chemically:
• Molecules rearrange with other molecules to make new substance
• Can be production of flames
• Color change
• Bubbling/fizzing
• Temp. change
• change in composition
Sliding or rolling friction
Answer:
1. 12.6 moles
2. 8.95 moles
3. 2A + 5B → 3C
4. 48 moles
Explanation:
1. 2Fe + 3Cl₂ → 2FeCl₃
We assume the chlorine in excess. Ratio is 2:2
2 moles of Fe, can produce 2 moles of chloride
12.6 moles of Fe will produce 12.6 moles of chloride.
2. 2Fe + 3Cl₂ → 2FeCl₃
For the same reaction, first of all we need to convert the mass to moles:
500 g . 1mol / 55.85 g = 8.95 mol
As ratio is 2:2, the moles we have are the same, that the produced
4. The reaction for the combustion is:
2C₂H₆ (g) + 7O₂ (g) → 4CO₂ (g) + 6H₂O (l)
We assume the oxygen in excess.
Ratio is 2:6, so 2 mol of ethane produce 6 moles of water
Therefore 16 moles of ethane may produce (16 .6) / 2 = 48 moles
Mass of electrons are not included when calculating the atomic mass of element. Atomic mass of the element is equal to proton + neurons. Example the the mass number of Nitrogen can be calculated as 7 protons + 7 neutrons to give 14 . thus nitrogen has a mass number of 14
Answer:
Explanation:
Subscripts are numbers written after elements, subscripts indicate how many of each atom there are in a compound.
