The age of painting was determined from the decay kinetics of the radioactive Carbon -14 present in the painting sample.
Given that the half life of Carbon-14 is 5730 years.
Radioactive decay reactions follow first order rate kinetics.
Calculating the decay constant from half life:
λ
= 
= 
Setting up the radioactive rate equation:
Where 
k = decay constant =
ln 0.125 = 
-2.079=
t=
= 17185 years
t = 17185 years
Therefore age of the painting based in the radiocarbon -14 dating studies is 17185 years
Answer: 625 kj/mol
Explanation:
As shown below this expression gives the activation energy of the reverse reaction:
EA reverse reaction = EA forward reaction + | enthalpy change |
1) The activation energy, EA is the difference between the potential energies of the reactants and the transition state:
EA = energy of the transition state - energy of the reactants.
2) The activation energy of the forward reaction given is:
EA = energy of the transition state - energy of [ NO2(g) + CO(g) ] = 75 kj/mol
3) The negative enthalpy change - 250 kj / mol for the forward reaction means that the products are below in the potential energy diagram, and that the potential energy of the products, [NO(g) + CO2(g) ] is equal to 375 kj / mol - 250 kj / mol = 125 kj/mol
4) For the reverse reaction the reactants are [NO(g) + CO2(g)], and the transition state is the same than that for the forward reaction.
5) The difference of energy between the transition state and the potential energy of [NO(g) + CO2(g) ] will be the absolute value of the change of enthalpy plus the activation energy for the forward reaction:
EA reverse reaction = EA forward reaction + | enthalpy change |
EA reverse reaction = 375 kj / mol + |-250 kj/mol | = 375 kj/mol + 250 kj/mol = 625 kj/mol.
And that is the answer, 625 kj/mol
Answer. Chemical reaction had occurred and both the powders are different substances.
Explanation:
As density is an intensive property of the substance.Which means that different substance have different densities.
Density = 
Density of powder 1, 
Density of powder 2, 
On comparing both the densities of the powders we can say that both the substances are different. So we can conclude that the chemical reaction had occurred.
Answer:
Explanation:
So basically it just asking you question about that surtain subject .
Answer:
0.129g MgCl2
Explanation:
For this we need to understand the concept of molarity.
Molarity is number of moles of solute/litres of solution
M=n/L
Here we are given molarity of 0.054M and volume of 25ml. we just plug this in formula to find moles of MgCl2
0.054=x/(25/1000) (we divided 25 by 1000 to convert it to litres of solution)
x=0.00135 moles of MgCl2 (we are not done yet the question asks for grams so to convert to grams we multiply by molar mass of MgCl2.)
0.00135molesMgCl2 x 95.211g MgCl2/1molMgCl2
= 0.129g MgCl2
