1070 hours.
1 mole of iron-59 would mass 59 grams, so 0.133 picograms would be 0.133x10^-12 / 59 = 2.25x10^-15 moles of iron-59. Multiplying by Avogadro's number, we can determine the number of atoms of iron-59 we have, so: 2.25x10^-15 * 6.02214x10^23 = 1.35x10^9
Since we have 242 decays over a period of 1 second, we can divide the
number of atoms left by the original number of atoms
(1350000000 - 242)/1350000000
= 1349999758/1350000000
= 0.999999820740741
And calculate the logarithm to base 2 of that quotient.
ln(0.999999820740741)/ln(2)
= -1.79259275281191x10^-7/0.693147180559945
= -2.58616467481524x10^-7
The reciprocal of this number will be the half life in seconds. So
-1/2.58616467481524x10^-7
= -3866729.79388461
And dividing by 3600 (number of seconds in an hour) will give the half-life in
hours.
-3866729.79388461 / 3600 = -1074.091609
So the half life in hours to 3 significant figures is 1070 hours.
Dividing that figure by 24 gives a half life of 44.58 days which is in pretty close agreement to the official half-life of 44.495 days for iron-59.
Responder:
2H2 + O2 → 2H2O
CaO + H2O → Ca (OH) 2
Fe + S → FeS
H2SO3 → SO2 + H2O
CaCO3 → CaO + CO2
Explicación:
2H2 + O2 → 2H2O
2 moléculas de hidrógeno gaseoso reaccionan con oxigente para producir 2 moléculas de agua
CaO + H2O → Ca (OH) 2
El óxido de calcio reacciona con el agua para producir hidróxido de calcio.
Fe + S → FeS
El hierro reacciona con el azufre para producir sulfuro de hierro.
H2SO3 → SO2 + H2O
Por descomposición, el ácido sulfuroso se descompone para producir dióxido de azufre y agua.
CaCO3 → CaO + CO2
El carbonato de calcio se descompone para producir óxido de calcio y dióxido de carbono.
Answer:
Answer: A) .346 M
Explanation:
Given:
- 450 mL
- .5 M soln
-200 mL water
1) Convert mL to L
450 mL = .45 L
200 mL = .2 L
2) Find mols in solution
.5 M = x/.45 L
x = .225 mol
3) Find total volume of solution
.45 L + .2 L =.65 L
4) Find new molarity
molarity (M) = mols solute/ L solution
y = .225 mol (from step 2)/ .65 L (from step 3)
y = .346 M
Answer: A) .346 M
Answer: During the summer, the sun's rays hit the Earth at a steep angle. ... Also, the long daylight hours allow the Earth plenty of time to reach warm temperatures. During the winter, the sun's rays hit the Earth at a shallow angle. These rays are more spread out, which minimizes the amount of energy that hits any given spot.
