Answer:
a) 4869 kj will be released
b) 43.86 g of octane
Explanation:
The heat of combustion is the amount of heat released when one mole of a substance reacts with enough oxygen
since the heat of combustion is per mol of combustible substancewjat we are required to do in this problem is calculate number moles in the reactions although in a different manner
a) MW C3H6O = 158 g/ mol
mol C3H6O = 158 g × 1 mol/ 58.08 g
= 2.72 - 1790 kj / mol ×2.72 mol = 4869 kj
b) Here we are asked the mass of octane to produce 1950 kj of heat knowing that per mole of octane we get 5074.1 kj then
1 mol / 5074.1kj × 1950 kj= 0.384 mol
mass C8H18 = 0.384 mol × 114.23 g/ mol = 43.86 g
2ZnS(s)+3O2(g) -> 2Zns(s) + 2SO3(g)
the above given equation is unbalanced as it contains 4 moles of sulphur in the output but in the input there are only two aoms of sulphur so to balance the equation we will write the equation as given under
balanced equation is
2ZnS(s)+3O2(g) -> 2Zn(s) + 2SO3(g)
In words:
When 2 moles of solid zinc sulfide reacts with 3 moles of oxygen gas gives 2 moles of solid zinc and 2 moles of sulphur trioxide gas.
The atom's center, or nucleus, is positively charged and the electrons that whirl around this nucleus are negatively charged, so they attract each other. The reason the force is strong is because the atom is so small. The distance between the nucleus and the electrons is about 1 Angstrom (named after a famous scientist); this is 0.00000001 cm (10-8 cm) or about 4 billionths of an
Answer:
(a) dew condensing on a leaf
(c) ice cream melting
Explanation:
The process which can be reversed by changing the temperature , i.e. , by increasing or decreasing the temperature , is called the <u>reversible process</u> .
From the question ,
- dew condensing on a leaf is a reversible process ,
As the water on the leaf can be changed to gaseous state by increasing the temperature .
The process of condensation and evaporation are reversible of each other .
The melted ice cream can be solidified again by reducing its temperature , hence , it is a reversible process .
- an egg turning hard when boiled and the batter cooking on a hot griddle
They both are irreversible process , and by changing the temperature , we can not get back the original substance .
Answer:
Final temperature = 91.75 °C
Explanation:
Given data:
Mass of water = 45 g
Initial temperature = 12 °C
Energy required = 15 Kj (15000 j)
Final temperature = ?
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
Solution:
Q = m.c. ΔT
15000 j = 45 g × 4.18 j/g.°C × (T2 -T1)
15000 j = 45 g × 4.18 j/g.°C × (T2- 12 °C)
15000 j = 188.1 J/°C × (T2- 12 °C)
15000 j / 188.1 J/°C = T2- 12 °C
79.745 °C = T2 - 12 °C
T2 = 79.745 °C + 12 °C
T2 = 91.75 °C
