All categories

3 years ago

Iodine-131 decays with a half-life of 8.02

1 answer:

3 0

Radioactive material undergoes 1st order decay kinetics.

For 1st order decay, half life = 0.693/k

where k = rate constant

k = 0.693/half life = 0.693/8.02 = 0.0864 day-1

Now, for 1st order reaction,
k = $\frac{2.303}{t} X log \frac{initial.conc}{final.conc}$

Given: t = 6.01d, initial conc. = 5mg

∴0.0864 = $\frac{2.303}{6.01} X log \frac{5}{final.conc}$
∴ final conc. = 2.975 mg

You might be interested in

Which statement correctly describes potassium iodide, KI? There is a one-to-one ratio of potassium ions to iodide ions. Potassiu

elena-14-01-66 [18.8K]

The answer is there is a one-to-one ratio of potassium ions to iodide ions.

Explanation :

- (K) belongs to Alkali metals in group (1A) that contains (1) electron in the outermost energy level, whereas, (I) is from halogens in group (7A) that contains (7) electron in the outermost energy level.

- To achieve stability, both atoms tend to reach the nearest noble state (outermost level occupies 8 electrons). Therefore, (K) loses its outer electron and gives it to (I) which now has a completely filled outer level and an ionic bond is formed between the two.

- The valency (number of electrons lost, gained or shared) of both atoms is equal ”monovalent” which means one-to-one ratio..

5 0

3 years ago

Read 2 more answers

Which fact below is describing a base?

QveST [7]

7 to 49 10 to 100. 30 Secs. 3. What is the pH value of pure water? 0 3 7 10 ... How do acids taste? bitter sour sweet salty. 30 Secs. 7. How do bases taste? bitter ... 8. Which kind of solution would react with a metal? acidic basic neutral water ... cocoa has a bitter taste. It is most likely which of the following? acid base neutral

6 0

3 years ago

With white light, a team measured a 0.7% percent change with 3.5g of plant matter in a one liter container. Convert

Strike441 [17]

moles CO₂ = 5.57.10⁻⁴

<h3>Further explanation </h3>

A mole is a number of particles(atoms, molecules, ions) in a substance

Can be formulated :

$\tt mol=\dfrac{mass}{MW}$

0.7% percent change with 3.5g of plant matter

mass :

$\tt 0.7\%\times 3.5~g=0.0245~g$

moles :

$\tt moles=\dfrac{0.0245}{44}=0.000557=5.57.10^{-4}$

5 0

3 years ago

What is the percent composition of hydrogen in NH4HCO3?

Readme [11.4K]

To find the Percent Composition of an atom, you use this formula:
Mass of element in the compound you're studying on ( in this case it's 5 since there is 5 Hydrogens) over the mass of the compound (which is here 79), Multiplied by 100 since you want a percent.
So we get:
$\frac{5}{79} * 100$
So you get about:
$0.063 * 100$
$6.3$

So, the percent composition of Hydrogen in NH4HCO3 is 6.3%

Hope this Helps! :D

7 0

3 years ago

Read 2 more answers

T/F___ At the eutectic composition, an alloy can solidify at a constant temperature.___ For effective dispersion strengthening,

azamat

Answer:

TRUE
FALSE
TRUE
FALSE
FALSE
TRUE

Explanation:

At the eutectic composition, an alloy can solidify at a constant temperature : TRUE . this is because at eutectic composition the type of reaction that takes place there is invariant reaction in its thermal equilibrium
For effective dispersion strengthening, the dispersed phase should be needle-like, as opposed to round : FALSE. because the rounded shape will not cause a crack.
Intermetallic compounds are usually hard and brittle : TRUE. because Intermetallic compounds prevents dislocation movements and this makes them brittle and hard
For the effective dispersion and strengthening, the dispersed phase should be continuous : FALSE. this is because the dispersed precipitate must be small and not continuous
Stoichiometric intermetallic compounds exist over a range of compositions : FALSE
Faster solidification results in smaller interlamellar spacing : TRUE

4 0

3 years ago