8.9 g/cm3 since density equals mass/volume or m/v you just divide 89 by 10 to get 8.9
Answer: 12.5 moles NaNO3
Explanation: solution attached.
First balance predict the products
Na+ Mg( NO3)2 => Mg + NaNO3
Next balance the chemical equation
2 Na + Mg(NO3)2 => Mg + 2 NaNO3
Solve for the moles of Na
175 g Na x 1 mole Na/ 14 g Na
Next compare the mole ratios of Na and NaNO3 based from the balanced equation.
2 moles Na : 2 moles NaNO3
1) Data:
<span>initial decay rate, No =16,800 disintegrations/min
final decay rate, Nf = 10,860 disintegrations/min
t = 28.0 days
t half-life =?
2) Formulas
Radioactive disintegration =>
Nt = No * e ^ (-kt)
t half-life = ln (2) / k
3) Solution
From Nt = No * e^ (-kt) =>
Nt / No = e ^ (-kt)
=> -kt = ln (Nt / No)
=> kt = ln (No/Nt)
=> k = ln (No / Nt) / t
=> k = ln (16,800 / 10,860) / 28 days = 0.01558 days^ -1
From t half-life = ln(2) / k
t half-life = ln(2) / (0.01558 days^-1) = 44.5 days.
Answer: 44.5 days.
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Answer:it reacts chemically to produce heat and gas with rapid expansion of matter. It is a rapid chemical reaction
Explanation:
The
equation for the photosynthesis reaction in which carbon dioxide and water
react to form glucose is .
The hear reaction is the difference between the bond dissociation energies in
the products and the bond dissociation energies of the reactants
The
reactant molecules have 12 C = O, 12 H - O bonds while the product molecules
have 5 C - C, 7 C – O, 5 H – O, and 6 O = O bonds. The average bond
dissociation energies for the bonds involved in the reaction are 191 for C = O,
112 for H – O, 83 C –C, 99 C – H, 86 C – O, 119 O = O.
Substitute
the average bond dissociation energies in the equation for and
calculate as follows
=
[12 (C=O) + 12 (H-O)] – [5(C-C) + 7(C-H) + 7 (C-O) + 5(H-O) + 6(O=O)]
=
[12x191 kcal/mol + 12x112 kcal//mol] – [5x83 kcal/mol + 7x99 kcal/mol + 7x86
kcal/mol + 5x112 kcal/mol + 6x119 kcal/mol]
=
3636 kcal/mol – 2984 kcal/mol = 652 kcal/mol x 4.184 Kj/1kcal = 2.73x10^3 kJ/mol
So,
enthalpy change for the reaction is 652 kcal/mol or 2.73x10^3 kJ/mol
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