Explanation:
During a chemical change, a new kind of matter is formed. Examples are combustion, rusting of iron, precipitation and souring of milk.
Here are some of the properties of chemical change:
- They are not easily reversible
- It leads to the production of new kinds of matter.
- It involves change in mass.
- It requires a considerable amount of energy.
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Answer:
a. 50KCal
b. 400KCal
c. Same as (a) above
Explanation:
Given
To raise the temperature of 1kg of liquid water at 1°C requires 1KCal
To raise the temperature of 1kg of ice or water vapour by 1°C requires 0.5KCal
To melt 1kg of ice at 0°C requires 80KCal
To evaporate 1kg of liquid water sitting at 100°C requires 540KCal
a. How much heat is required to raise the temperature of 5 kg of liquid water by 20 C?
To raise the temperature of 5 kg of ice by 20°C requires:
5 kg * (0.5 kcal / kgC) * 20C
= 50 KCal
b. How much heat is required to melt 5 kg of ice at 0 C?
To melt an ice of 5 kg of ice at 0 C requires:
5 kg * (80 kcal / kg)
= 400 KCal
c. Same as (a) above
The absence of an unbalanced force, an object at rest will stay at rest and an object in motion will stay in motion.
When the balanced reaction equation is:
P4O10 + 6H2O→ 4 H3PO4
when we have the mass of P4O10 = 10 g and the molar mass of P4O10=284 g/mol & we have the molar mass of H3PO4 =98 g/mol so we can get the mass of H3PO4 by substitution by:
mass of H3PO4 = (mass of P4O10)/(molar mass of P4O10) * 4(mol of H3PO4)*molar mass of H3PO4
∴mass of H3PO4 = (10 / 284) * 4 * 98 = 13.8 g
