Hey there!
A half-life means after a certain amount of time, half of that substance will have decayed after that time.
An equation for exponential decay is the following:
y = a(1 - b)ⁿ
Where a is the original amount, b is the rate of decay, and n is time.
1000 is about 0.3 of a half life, 1000 divided by 138 days (3312 hours) is approximately 0.3.
Let's plug in values to that equation:
y = 321(1 - 0.5)^(0.3)
Simplify.
y = 260.73
There will be 260.73mg of polonium-210 remaining after 1000 hours.
Hope this helps!
Answer:
The temperature of the molecule will be increased by a factor of 9
Explanation:
The relationship between the temperature and the rms speed of a gas is given by
Vrms=√(3RT/MM)
Where R = Universal gas constant
T = Absolute temperature of the gas in kelvin
MM = Molar mass of the gas
Since from the question, only the rms speed and the temperature are said to change, the term 3R/MM can be represented by a constant k. The relationship then becomes Vrms=√kT
At the intitial speed, temperature = T1
Vrms=√(kT1 ) (1)
When the speed is increased by a factor of 3, the relationship becomes
(3V)rms=√(kT2 ) (2)
Dividing equation (2) by equation (1)
(3V)rms/Vrms =√(kT2 )/√(kT1 )
3=√(T2/T1 )
T2/T1 =9
The temperature of the molecule will be increased by a factor of 9
Answer:
the answer is B =the weighted average of the masses of the isotopes of the element
•3.9g of ammonia
•molar mass of ammonia = 17.03g/mol
1st you have to covert grams to moles by dividing the mass of ammonia with the molar mass:
(3.9 g)/ (17.03g/mol) = 0.22900763mols
Then convert the moles to molecules by multiplying it with Avogadro’s number:
Avogadro’s number: 6.022 x 10^23
0.22900763mols x (6.022 x 10^23 molecs/mol)
= 1.38 x 10^23 molecules