The general equation for radioactive decay is;
N = N₀e^(-λt)
x - decay constant (λ) - rate of decay
t- time
N - amount remaining after t days , since we are calculating the half life, amount of time it takes for the substance to to be half its original value, its N₀/2
N₀ - amount initially present
substituting the values
N₀/2 = N₀e^(-0.081t)
0.5 = e^(-0.081t)
ln (0.5) = -0.081t
-0.693 = -0.081t
t = 0.693 / 0.081
= 8.55
half life of substance is 8.55 days
Answer:
The mass of 0.280 mole sample of sodium hydroxide NaOH is 11.2 grams.
Explanation:
To know the mass in grams of 0.280 moles of sample of sodium hydroxide NaOH, you must know the molar mass of the compound, that is, the mass of one mole of a substance, which can be an element or a compound.
So you know:
- Na: 23 g/mole
- O: 16 g/mole
- H: 1 g/mole
So, the molar mass of NaOH is:
NaOH= 23 g/mole + 16 g/mole+ 1 g/mole= 40 g/mole
Then the following rule of three can be applied: if in 1 mole of sodium hydroxide there are 40 grams, in 0.280 moles how much mass is there?
mass= 11.2 grams
<u><em>The mass of 0.280 mole sample of sodium hydroxide NaOH is 11.2 grams.</em></u>
Answer:
10.9%.
Explanation:
The first thing to do in order to solve this question is to Determine the value for the volume of the the cube. This can be done by taking the cube root of the length of the cube;
The volume of the cube = (length of the cube)^3 = length × length × length = 1.72 × 1.72 × 1.72 =( 1.72)^3 = 5.09cm^3.
The next thing you do is to Determine the exponential density, the can be done by using the formula below;
The exponential density = mass/ volume = 55. 786/ 5.09 = 10.96 g/cm^3.
Therefore, the percent error = (true density of the cube - exponential density of the cube)÷ true density of the cube × 100.
Hence, the percent error = 12.30 - 10.96/12.30 × 100 = 10.9%.
Answer:
we know that it originally came from an animal, likely a bat. At this time, there is no evidence that animals play a significant role in spreading the virus that causesd
Explanation:
B. At the equivalence point of a titration of the [H+] concentration is equal to 7.
<h3>What is equivalence point of a titration?</h3>
The equivalence point of a titration is a point in titration at which the amount of titrant added is just enough to completely neutralize the analyte solution.
At the equivalence point in an acid-base titration, moles of base equals moles of acid and the solution only contains salt and water.
At the equivalence point, equal amounts of H+ and OH- ions combines as shown below;
H⁺ + OH⁻ → H₂O
The pH of resulting solution is 7.0 (neutral).
Thus, the pH at the equivalence point for this titration will always be 7.0.
Learn more about equivalence point here: brainly.com/question/23502649
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