Answer:
Most common insulation materials work by slowing conductive heat flow and--to a lesser extent--convective heat flow. Radiant barriers and reflective insulation systems work by reducing radiant heat gain. To be effective, the reflective surface must face an air space.
Explanation:
To be effective, the reflective surface must face an air space.
Answer: a) : negative
b) : positive
c) : positive.
d) : negative
e) : positive.
f) : positive.
Explanation:
Entropy is the measure of randomness or disorder of a system. If a system moves from an ordered arrangement to a disordered arrangement, the entropy is said to decrease and vice versa.
is positive when randomness increases and is negative when randomness decreases.
a)
As ions are moving to solid form , randomness decreases and thus sign of is negative.
b)
As solid is changing to gas, randomness increases and thus sign of is positive.
c)
As 2 moles of reactants are converted to 4 moles of products , randomness increases and thus sign of is positive.
d)
As gas is changing to solid, randomness decreases and thus sign of is negative.
e)
As 7 moles of reactants are converted to 8 moles of products , randomness increases and thus sign of is positive.
f)
As solid is changing to gas, randomness increases and thus sign of is positive.
Explanation:
The structures of both acetone and propanal are shown below:
In the formula of propanal there is -CHO functional group at the end.
In acetone -CO- group is present in the middle that is on the second carbon.
The molecular formula is C3H6O.
Both have same molecular formula but different structural formulas.
Combustion equation of n-hexane:
2C₆H₁₄ + 19O₂ → 12CO₂ + 14H₂O
a)
Assuming we have 100 moles of air,
Oxygen = 20.9 moles
n-hexane required = 20.9/19 x 2
= 2.2 moles
LFL = Half of stoichometric amount = 2.2 / 2 = 1.1
LFL n-hexane = 1.1%
b)
1.1 volume percent required for LFL
1.1% x 1
= 0.0011 m³ of n-hexane required