Answer:
An increase in the speed of the molecules competes with the attraction between molecules and causes molecules to move a little further apart. Cooling a liquid decreases the speed of the molecules.
Explanation:
The enthalpy of the reaction is 100 kJ and the reaction is endothermic in nature.
<u>Explanation:</u>
Enthalpy of any chemical reaction is the measure of the difference in the energy utilized for performing a reaction. As in the present case, it is stated that the initially, a chemical reaction has 356 kJ of energy and after ending the chemical reaction has 456 kJ of energy.
This means the energy is increased after the chemical reaction. So the heat energy is absorbed during the reaction. This kind of chemical reaction where the products are formed by absorbing energy from the surrounding is termed as endothermic reaction.
Enthalpy = Energy absorbed = 456-356 =100 kJ.
So, the enthalpy of the reaction is 100 kJ. And as the enthalpy is positive which means the energy is absorbed from the surroundings, so the reaction is endothermic in nature.
Answer:
270 Joules
Explanation:
The specific heat capacity equation will be used for this question i.e.
Q = m. c. ΔT
Where; Q = Amount of heat
m = mass of substance
C = specific heat capacity of
substance
ΔT = change in temperature
(Final temp - initial temp)
However, for this unknown metal, we need to find the specific heat first by saying; C = Q / mΔT
Q= 135J, C=?, m= 10g, ΔT = (40-25 = 15°C)
C = 135 / 15 × 10
C = 135/150
C = 0.9 J/g°C
If the specific heat capacity of the unknown metal is 0.9 J/g°C, then at a mass of 20.0g, and a ΔT of 15°C, the amount of heat needed is:
Q = m. c. ΔT
Q = 20 × 0.9 × (40-25)
Q = 18 × 15
Q = 270J
270 Joules of heat is needed to increase the temperature of 20g of the metal from 25 - 40°C
A physical change. When a physical change occurs the chemical composition of the substance doesn't change. Some examples of physical changes are melting, freezing, vaporization, and condensation.
Molality= mol/ Kg
if we assume that we have 1 kg of water, we have 3.19 moles of solute.
the formula for mole fraction --> mole fraction= mol of solule/ mol of solution
1) if we have 1 kg of water which is same as 1000 grams of water.
2) we need to convert grams to moles using the molar mass of water
molar mass of H₂O= (2 x 1.01) + 16.0 = 18.02 g/mol
1000 g (1 mol/ 18.02 grams)= 55.5 mol
3) mole of solution= 55.5 moles + 3.19 moles= 58.7 moles of solution
4) mole fraction= 3.19 / 58.7= 0.0543
