Answer:
30.25°C
Explanation:
The calorimeter is an equipment used to measure the combustion enthalpy of a substance. The heat loss in the reaction is used to heat the water and the equipment. By the conservation of energy:
Qcombustion + Qcalorimeter + Qwater = 0
Because there is no phase change:
Qcalorimeter = C*ΔT, where C is the heat capacity, and ΔT the variation in temperature (final - initial)
Qwater = m*c*ΔT, where m is the mass, and c is the specific heat (4.184 J/g°C).
The molar mass of lactose is 342.3 g/mol, so the number of moles in 2.50 g is:
n = mass/molar mass
n = 2.50/342.3
n = 0.0073 mol
Qcombustion = -5652 kJ/mol * 0.0073 mol
Qcombustion = -41.28 kJ
Qcombustion = - 41280 J
Thus,
-41280 + 1630*(T - 24.58) + 1350*4.184*(T - 24.58) = 0
(T - 24.58) * (1630 + 5648.4) = 41280
7278.4(T - 24.58) = 41280
T - 24.58 = 5.67
T = 30.25°C
Answer: Calories
Explanation: One calorie is the amount of energy required to raise one gram of water one degree Celsius
Answer: B.
Explanation:
When the electron changes levels, it decreases energy and the atom emits photons. The photon is emitted with the electron moving from a higher energy level to a lower energy level. The energy of the photon is the exact energy that is lost by the electron moving to its lower energy level.
Hope this helps!
Iron gains three electrons