solution:
The general form of the equation would be A = P x (1/2) ^ (t/h) where A = final amount, P = start amount, t = time (here in days) and h = half-life (has to be same units as t)
a) A = 192 x (1/2) ^ (15/5) = 192 x (1/2) ^3 = 192 x 1/8 = 24 mg
The mass of sulfur that has to burn to produce 4.5L SO2 at 300 c and 101 kPa is 3.05 grams (which is around answer B)
calculation
equation for reaction =S+ O2 = SO2
by use the ideal gas equation find the moles of SO2 formed
Ideal gas equation = PV=nRT where
P(pressure)= 101 KPa
V(volume)= 4.5 L
n(number of moles)=?
R(gas constant)= 8.314 L.Kpa/mol.k
T(temperature) = 300+ 273 =573 K
by making n the formula of the subject
n = PV/RT
n= (101 kpa x4.5 L) / ( 8.314 l.KPa/Mol.K x 573 K) = 0.0954 moles
by use of mole ratio between S to SO2 which is 1:1 the moles of SO2 is also 0.0954 moles
mass of SO2 = moles x molar mass
the molar mass of SO2 = 32 g/mol
therefore mass = 32 g/mol x 0.0954 = 3.05 grams(answer B)
The amount of the certain molecule in the brain
Answer:
The answer to your question is: ΔH = 1637.8
Explanation:
Hess' law: This law states that the enthalpy change can be calculated even if it is not calculated directly.
"if a chemical change takes place by several routes, the overall enthalpy change is the same regardless the route".
Process
A) N2(g)+O2(g)—->2NO(g) Δ H= -180.5
B) N2(g) + 3H2(g) ——> 2NH3(g) Δ H= -91.8
C)2H2(g)+ O2(g) —-> 2H2O(g) Δ H= -486.6
The result must be:
4NH3(g)+5O2(g)—->4NO(g)+6H2O(g)
Turn letter B and multiply it by 2
4NH3 ⇒ 2N2 + 6H2 ΔH = 183.6
Multiply letter A by 2
2N2 + 2O2 ⇒ 4 NO ΔH = -361
Multiply letter C by 3
6H2 + 3O2 ⇒ 6H2O ΔH = -1459.8
Finally we add the equations up and simplify then:
4NH3 + 5O2 ⇒ 4NO + 6 H2O
And we add the ΔH = 183.6 - 361 - 1459.8
= -1637.8
