Answer:
-26.125 kj
Explanation:
Given data:
Mass of water = 250.0 g
Initial temperature = 30.0°C
Final temperature = 5.0°C
Amount of energy lost = ?
Solution:
Formula:
Q = m.c. ΔT
Q = amount of heat absorbed or released
m = mass of given substance
c = specific heat capacity of substance
ΔT = change in temperature
ΔT = T2 - T1
ΔT = 5.0°C - 30.0°C
ΔT = -25°C
Specific heat of water is 4.18 j/g.°C
Now we will put the values in formula.
Q = m.c. ΔT
Q = 250.0 g × 4.18 j/g.°C × -25°C
Q = -26125 j
J to kJ
-26125 j ×1 kj /1000 j
-26.125 kj
Answer:
Option B : burning of wood
Explanation:
Chemical change is a change where a new substance is created like when you will bur wood you get ash this is a new substance, so burning of wood is a chemical change.
Given
Mass of NO - 824 g
Molar mass of NO - 30.01g/mol
No of moles of NO = Given mass/Molar mass
No of moles of NO = 824/30.01= 27.45 mole
Hence 27.5 moles of NO are formed!
The molecular formula of methylpropan-1-ol is C4H10O, so the complete combustion equation is: C4H10O + 6O2 --> 4CO2 + 5H2O. This mean to completely combust 1.0mol of methylpropan-1-ol, 6 mol of O2 is required. Molar mass of O2 is 32 g/mol, so 32g/mol x 6mol = 192 g of O2 is required. At room temperature and pressure, the density of O2 is 1.3315 g/L (this can be obtained by density of gas = P/RT). So the volume of O2 = mass/density = 192g/1.3315(g/L) = 144 L = 144 dm3. The answer is B.
