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3 years ago

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1 answer:

3 0

In 52.6 mins the 10 mg of iodine will be divided by its half-life which is 2 it will become 5 mg (in 52.6 minutes ) and same procedure will be followed until it reach 99% out of the patient's system.

The answer is 368 minutes will it takes the iodine to be absorbed in one's system.

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A 0.200 M solution of a weak acid, HA, is 9.4% ionized. Using this information, calculate Ka for HA.

slavikrds [6]

${ \qquad\qquad\huge\underline{{\sf Answer}}}$

Let's solve ~

Initial concentration of weak acid HA = 0.200 M

and dissociation constant ( ${ \alpha}$ ) is :

$\qquad \sf \dashrightarrow \: \alpha = \frac{dissociation \: \: percentage}{100}$

$\qquad \sf \dashrightarrow \: \alpha = \frac{9.4}{100} = 0.094$

Now, at initial stage :

$\textsf{ Conc of HA = 0.200 M}$

$\textsf{Conc of H+ = 0 M}$

$\textsf{Conc of A - = 0 M}$

At equilibrium :

$\textsf{Conc of HA = 0.200 - 0.094(0.200) = 0.200(1 - 0.094) = 0.200(0.906) = 0.1812 M}$

$\textsf{Conc of H+ = 0.094(0.200) = 0.0188 M}$

$\textsf{Conc of A - = 0.094(0.200) = 0.0188 M}$

Now, we know :

$\qquad \sf \dashrightarrow \: { K_a = \dfrac{[H+] [A-]}{[HA]}}$

( big brackets represents concentration )

$\qquad \sf \dashrightarrow \: { K_a = \dfrac{0.0188×0.0188}{0.1812}}$

$\qquad \sf \dashrightarrow \: { K_a = \dfrac{0.00035344}{0.1812}}$

$\qquad \sf \dashrightarrow \: { K_a \approx 0.00195 }$

$\qquad \sf \dashrightarrow \: {K_a \approx 1.9 × {10}^{-3} }$

7 0

2 years ago

354.5 g of chlorine gas is held with a fixed volume of 70.0 L. What is the pressure of the gas in atmospheres if it’s temperatur

zaharov [31]

Answer: The pressure of the gas in atmospheres is 1.76

Explanation:

According to ideal gas equation:

$PV=nRT$

P = pressure of gas = ?

V = Volume of gas = 70.0 L

n = number of moles = $\frac{\text {given mass}}{\text {Molar mass}}=\frac{354.5g}{71g/mol}=5moles$

R = gas constant = $0.0821Latm/Kmol$

T =temperature = $30.0^0C=(30.0+273)K=300.0K$

$P=\frac{nRT}{V}$

$P=\frac{5\times 0.0821Latm/K mol\times 300K}{70.0L}=1.76$

Thus the pressure of the gas in atmospheres is 1.76

7 0

3 years ago

explain why the first ionization energy of krypton is greater than the first ionization energy of bromine

4vir4ik [10]

Answer:

The atomic radius of krypton is similar to that of bromine. However, the effective nuclear charge of krypton is greater than that of bromine.

Explanation:

Ionizing an atom require moving an electron from the electron cloud of the atom to a point infinitely far away from the atom. The first ionization energy of this atom is the energy change in this process.

The electron and the nucleus are oppositely-charged. There is an electrostatic force between the two. Removing the electron requires overcoming this attraction. The size of the energy input depends on the electrostatic potential energy of the electron (the gravitational potential energy is much smaller than the electrostatic potential energy.) The separation between the electron and the nucleus is much larger than their radii. Both objects can be considered as point charges. Coulomb's Law gives the electrostatic potential energy of the two point charge that are close to each other.

$\displaystyle \text{Electrostatic Potential Energy} = -\frac{k\cdot (q_1\cdot q_2)}{r}$ ,

where

$k$ is Coulomb's constant,
$q_1$ and $q_2$ are the two charges, and
$r$ is the separation between the two charges.

Krypton and bromine are right next to each other in the same period. Their atomic radii will be similar to each other. The separation $r$ between the outermost electron and the nucleus will also be similar for the two elements.

The first charge $q_1$ can be the electron. However, data show that for elements after helium, the second charge $q_2$ is smaller than the sum of charges on all protons in the nucleus. It turns out that the inner shell electrons (all of which are also negative) repel electrons in the outermost valence shell. The effective nuclear charge $Z_\text{eff}$ of a neutral atom is approximately the same as the number of protons minus the number of non-valence electrons. That number will be slightly larger for krypton than for bromine. As a result, the electrostatic potential energy on a 4p (the outermost orbital for both Kr and Br) electron of krypton will be more negative than that on a 4p electron in bromine. Removing that electron will take more energy in Kr than in Br. The first ionization energy of Kr is hence greater than that of Br.

8 0

3 years ago

Read 2 more answers

Perform the following for Part C of this lab:

kaheart [24]

Answer:

a. 0.0110 L

b. 0.0020 L

c. 0.011 mol

d. 5.5 M

e. 0.66 g

f. 33%

Explanation:

There is some info missing. I will use some values to show you the procedure and then you can replace them with your values.

Titrant (NaOH) concentration: 1.0 M

Vinegar volume: 2.0 mL

Initial buret reading (initial NaOH volume): 0.1 mL

Final buret reading (final NaOH volume): 11.1 mL

a. Calculate the volume of NaOH that was added to the vinegar. Convert this volume to liters. Show your work.

The volume of NaOH is the difference between the final and the initial buret reading.

11.1 mL - 0.1 mL = 11.0 mL × (1 L/1000 mL) = 0.0110 L

b. Convert the measured volume of vinegar to liters. Show your work.

2.0 mL × (1 L/1000 mL) = 0.0020 L

c. Calculate the moles of NaOH using the volume and molarity of NaOH. Show your work. moles = molarity x volume

moles = molarity × volume

moles = (1.0 mol/L) × 0.0110 L = 0.011 mol

d. Since the reaction ratio is 1:1, the moles of acetic acid in the vinegar is equal to the moles of NaOH reacted during the titration. Calculate the molarity of the acetic acid in the vinegar. Show your work. molarity = moles / volume

molarity = moles / volume

molarity = 0.011 mol/0.0020 L = 5.5 M

e. Calculate the grams of acetic acid in the vinegar. Show your work. mass = moles x molar mass (g/mol)

mass = moles × molar mass

mass = 0.011 mol × 60.05 g/mol = 0.66 g

f. Assuming that the density of vinegar is very close to 1.0 g/mL, the 2.0 mL sample of vinegar used in the titration should weigh 2.0 g. Use this to calculate the mass % of acetic acid in the vinegar sample. mass % = (mass acetic acid / mass vinegar) * 100%

mass % = (mass acetic acid / mass vinegar) * 100%

mass % = (0.66 g /2.0 g) * 100% = 33%

6 0

3 years ago

In which tool are uranium atoms split to make electricity?

Anuta_ua [19.1K]

I'm assuming this refers to nuclear fission, which is in fact used to create heat, causing steam to spin turbines.
In which case, Uranium atoms are split by absorbing neutrons inside the reactor of a nuclear power station.

8 0

3 years ago