When sodium is put in water, it quickly reacts according to the following equation: 2 Na (s) + 2H_2O (II) > 2NaOH (aq) + H_2
(g)
if 4.52 moles of Na react with an excess of water, how many grams of H_2 are formed?
if 4.52 moles of Na react with an excess of water, how many grams of H_2 are formed?
1 answer:
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Within the options, we have four organic compounds. Let's see what the skeletal structure of the compounds is in order to identify them better:
The first compound CH3OCH3 has two methyl groups linked by a carbon atom, this type of compound is called an Ether
The second compound has a double bond, it is badly written but it seems that is an alkene.
The third compound has two methyl groups linked by nitrogen atoms, therefore will be an amine.
The last compound has a hydroxyl group, therefore it is an alcohol
Answer:
CH3OCH3 Ether
CH2CH2CHCH2CH3 Alkene
CH3NHCH3 Amine
CH3CH(OH)CH₂CH3 Alcohol
Answer : The correct answer is 96.68 yrs
Radioactivity Decay :
it is a process in which a nucleus of unstable atom emit energy in form of radiations like alpha particle , beta particle etc .
Radioactive decay follows first order kinetics , so its rate , rate constant , amount o isotopes can be calculated using first order equations .
The first order equation for radioactive decay can be expressed as :
----------- equation (1)
Where : N = amount of radioisotope after time "t"
N₀ = Initial amount of radioisotope
k = decay constant and t = time
Following steps can be used to find time :
1) To find deacy constant :
Decay constant can be calculated using half life . Decay constant and half life can be related as :
---------equation (2)
Given : Half life of Strontium -90 = 28.8 years
Plugging value of in above formula (equation 2) :
Multiply both side by k
Dividing both side by 28.8 yrs
(ln 2 = 0.693 )
k = 0.0241 yrs⁻¹
Step 2 : To find time :
Given : N₀ = 10.3 ppm N = 1.0 ppm k = 0.0241 yrs⁻¹
Plugging these value in equation (1) as :
(ln 0.0971 = - 2.33 )
Dividing both side by - 0.0241 yrs⁻¹
t = 96.68 yrs
Hence the concentration of Strontium-90 will drop from 10.3 ppm to 1.0 ppm is 96.68 yrs