4.14x10^-3 per minute
First, calculate how many atoms of Cu-61 we initially started with by
multiplying the number of moles by Avogadro's number.
7.85x10^-5 * 6.0221409x10^23 = 4.7273806065x10^19
Now calculate how many atoms are left after 90.0 minutes by subtracting the
number of decays (as indicated by the positron emission) from the original
count.
4.7273806065x10^19 - 1.47x10^19 = 3.2573806065x10^19
Determine the percentage of Cu-61 left.
3.2573806065x10^19/4.7273806065x10^19 = 0.6890455577
The formula for decay is:
N = N0 e^(-λt)
where
N = amount left after time t
N0 = amount starting with at time 0
λ = decay constant
t = time
Solving for λ:
N = N0 e^(-λt)
N/N0 = e^(-λt)
ln(N/N0) = -λt
-ln(N/N0)/t = λ
Now substitute the known values and solve:
-ln(N/N0)/t = λ
-ln(0.6890455577)/90m = λ
0.372447889/90m = λ
0.372447889/90m = λ
0.00413830987 1/m = λ
Rounding to 3 significant figures gives 4.14x10^-3 per minute as the decay
constant.
Answer:
The molarity (M) of the following solutions are :
A. M = 0.88 M
B. M = 0.76 M
Explanation:
A. Molarity (M) of 19.2 g of Al(OH)3 dissolved in water to make 280 mL of solution.
Molar mass of Al(OH)3 = Mass of Al + 3(mass of O + mass of H)
= 27 + 3(16 + 1)
= 27 + 3(17) = 27 + 51
= 78 g/mole
= 78 g/mole
Given mass= 19.2 g/mole
Moles = 0.246
Volume = 280 mL = 0.280 L
Molarity = 0.879 M
Molarity = 0.88 M
B .The molarity (M) of a 2.6 L solution made with 235.9 g of KBr
Molar mass of KBr = 119 g/mole
Given mass = 235.9 g
Moles = 1.98
Volume = 2.6 L
Molarity = 0.762 M
Molarity = 0.76 M
<span>-5230 J
Given the above data, the piece of metal raised the temperature of 250.0 grams of water from 20.0°C to 25.0°C. So there was a change of 5.0°C
The specific heat of water is 4.184 joules per gram which is the amount of energy needed to rais</span>
The rate of reaction may be determined using the concentration-time graph of either a reactant or product. The slope of the graph helps in determining the rate of reaction. If the rate of reaction increases, the magnitude of the slope of the graph will increase. This indicates that more reactant is being consumed per unit time, or, in the case of the product, more product is being produced per unit time.
The kilograms of matter that would have to be converted into energy to produce 24. 0 megajoules of energy is
M=2.67*10^(-10)kg. This is further explained below.
<h3>
How many kilograms of matter would have to be converted into energy to produce 24. 0 megajoules of energy?.</h3>
Generally, Energy is simply defined as the physically and mentally stamina necessary for prolonged physical or mental action.
inconclusion, Einstein equation of relativity
E=MC^2
Therefore
M=e/c^2
M=24*10^6/3*10^8
M=2.67*10^(-10)kg
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