The half-life of Zn-71 is 2.4 minutes. If one had 100.0 g at the beginning, how many grams would be left after 7.2 minutes has elapsed? Report your answer to 1 decimal place.

Answer:

The median would be 6700

Explanation:

Arrange data values from lowest to highest value

The median is the data value in the middle of the set

.

Ordering a data set x1 ≤ x2 ≤ x3 ≤ ... ≤ xn from lowest to highest value, the median x˜ is the data point separating the upper half of the data values from the lower half.

If the size of the data set n is odd the median is the value at position p where

Formula for the median

p=n+12

x˜=xp

If n is even the median is the average of the values at positions p and p + 1 where

p=n2

x˜=xp+xp+12

If there are 2 data values in the middle the median is the mean of those 2 values.

Answer:

2.77 mol/kg

Explanation:

Molality is a sort of concentration that indicates the moles of solute in 1kg of solvent. In this case our solvent is water and, if we consider water's density as 1g/mL, we determine that the mass of solvent is 750 g.

We convert the mass to kg → 750 g . 1kg /1000g = 0.750 kg

Our solute is the NaOH → 83 g.

We convert the mass to moles → 83 g . 1mol /40g = 2.075 mol

Molality (mol/kg) = 2.075 mol / 0.75kg = 2.77 m

Answer:

Spacecraft’s acceleration (a) = 0.10 N / 500 kg

Explanation:

Given:

Mass of Spacecraft (M) = 500 Kg

Force generate by engine (F) = 0.10 N

Find:

Spacecraft’s acceleration (a)

Computation:

F = Ma

0.10 = 500 (a)

a = 0.10 / 500

Spacecraft’s acceleration (a) = 0.10 N / 500 kg

The expression which can be used to find the spacecraft’s acceleration if its engine created a net force of 0.10 N is  0.10 N/500Kg.

We know that force is the product of the mass a body and its acceleration. The result of motion is the action of an unbalanced force. We have the following information;

Mass of the spacecraft = 500 kg

Force on the engine =  0.10 N

From Newton's law;

F = ma

F = force

m = mass

a = acceleration

a = F/m

acceleration = 0.10 N/500Kg

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Answer:

0.0002949 moles

Explanation:

Concentration = 2.02×10−2 M

Volume = 14.6 mL = 0.0146 L (Upon converting to litres)

Number of moles = ?

These variables are related by the fllowing equation;

Concentration = Number of moles / Volume

Number of moles = Concentration * Volume

Number of moles = 2.02×10−2 * 0.0146 = 0.0002949 moles

Answer:

Ca²⁺ and Cl⁻

Explanation:

In a chemical reaction, spectator ions are ions that are not involved in the reaction, that means are the same before and after the reaction.

In water, calcium hydroxide, Ca(OH)₂ is dissociated in Ca²⁺ and OH⁻. Also, hydrochloric acid, HCl, dissociates in H⁺ and Cl⁻. The reaction is:

Ca²⁺ + 2OH⁻ + 2H⁺ + 2Cl⁻ → 2H₂O + Ca²⁺ + 2Cl⁻

The ions that react are H⁺ and OH⁻ (Acid and base producing water)

And the ions that are not reacting, spectator ions, are:

Answer:

Methyl radical

Explanation:

A radical is any specie that contains an odd number of electrons. We must note that the greater the number of alkyl groups which are attached to a carbon atom that bears the odd electrons, the more the degree of delocalization of the odd electrons and consequently the more stable we expect the free radical to be.

Hence the order of free radical stability is; Methyl < Primary < Secondary < Tertiary. Hence, we can easily see that the methyl radical is the least stable free radical.

Answer: Methyl radical

Explanation:

Answer:

C. Electron cloud

the electron is around 1/2000 times the size of the proton.

If you imagine the proton a a marble in the middle of a football field, the electrons will revolve around the last row

Answer:

Below

Explanation:

Let n be the quantity of matter in the Calcium Bromide

● n = m/ M

M is the atomic weight and m is the mass

M of CaBr2 is the sum of the atomic wieght of its components (2 Bromes atoms and 1 calcium atom)

M = 40.1 + 2×79.9

● 0.422 = m/ (40.1+2×79.9)

●0.422 = m/ 199.9

● m = 0.422 × 199.9

● m = 84.35 g wich is 88.4 g approximatively

88.4 g approximatively is  the mass in grams of 0.442 moles of calcium bromide, CaBr2 ,therefore option (d) is correct.

Mass is the amount of matter that a body possesses. Mass is usually measured in grams (g) or kilograms (kg) .

To calculate mass in grams of 0.442 moles of calcium bromide, CaBr2,

Let n be the quantity of matter in the Calcium Bromide

M is the atomic weight and m is the mass

M of CaBr2 is the sum of the atomic weight of its components

Mass of  Ca = 40.1 , Mass of Br = 79.9

M = 40.1 + 2×79.9

  0.422 = m/ (40.1+2×79.9)

  0.422 = m/ 199.9

  m = 0.422 × 199.9

  m = 84.35 g which is 88.4 g approximatively .

Thus ,88.4 g approximatively is  the mass in grams of 0.442 moles of calcium bromide, CaBr2 , hence option (d) is correct .

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ANSWER

I need great answers

EXPLANATION

please rate my answer as great

Answer:

A) 3.17 g of Zn

Explanation:

Let's consider the reduction of Zn(II) that occurs in an electrolysis bath.

Zn⁺²(aq) + 2e⁻ → Zn(s)

We can establish the following relations:

The mass of Zn deposited under these conditions is:

[tex]24min \times \frac{60s}{1min} \times \frac{6.5C}{s} \times \frac{1mol\ e^{-} }{96,468C} \times \frac{1molZn}{2mol\ e^{-}} \times \frac{65.38g}{1molZn} = 3.17 g[/tex]

Answer:

A.) 3.17

Explanation:

I got it right in class!

Hope this Helps!! :))

Answer:

The concentration in mol/L =  4.342 mol/L

Explanation:

Given that :

mass of sodium chloride = 25.4 grams

Volume of the volumetric flask = 100 mL

We all know that the molar mass of sodium chloride NaCl = 58.5 g/mol

and number of moles = mass/molar mass

The number of moles of sodium chloride = 25.4 g/58.5 g/mol

The number of moles of sodium chloride = 0.434188 mol

The concentration in mol/L = number of mol/ volume of the solution

The concentration in mol/L = 0.434188 mol/ 100 × 10⁻³ L

The concentration in mol/L =  4.34188 mol/L

The concentration in mol/L =  4.342 mol/L

Answer:

B.3/5p

Explanation:

For this question, we have to remember "Dalton's Law of Partial Pressures". This law says that the pressure of the mixture would be equal to the sum of the partial pressure of each gas.

Additionally, we have a proportional relationship between moles and pressure. In other words, more moles indicate more pressure and vice-versa.

[tex]P_i=P_t_o_t_a_l*X_i[/tex]

Where:

[tex]P_i[/tex]=Partial pressure

[tex]P_t_o_t_a_l[/tex]=Total pressure

[tex]X_i[/tex]=mole fraction

With this in mind, we can work with the moles of each compound if we want to analyze the pressure. With the molar mass of each compound we can calculate the moles:

moles of hydrogen gas

The molar mass of hydrogen gas ([tex]H_2[/tex]) is 2 g/mol, so:

[tex]6g~H_2\frac{1~mol~H_2}{2~g~H_2}=~3~mol~H_2[/tex]

moles of oxygen gas

The molar mass of oxygen gas ([tex]O_2[/tex]) is 32 g/mol, so:

[tex]64g~H_2\frac{1~mol~H_2}{32~g~H_2}=~2~mol~O_2[/tex]

Now, total moles are:

Total moles = 2 + 3 = 5

With this value, we can write the partial pressure expression for each gas:

[tex]P_H_2=\frac{3}{5}*P_t_o_t_a_l[/tex]

[tex]P_O_2=\frac{2}{5}*P_t_o_t_a_l[/tex]

So, the answer would be 3/5P.

I hope it helps!

Answer:

0.107 mole of SO2.

Explanation:

1 mole of a gas occupy 22.4 L at standard temperature and pressure (STP).

With the above information, we can simply calculate the number of mole of SO2 that will occupy 2.4 L at STP.

This can be obtained as follow:

22.4 L contains 1 mole of SO2.

Therefore, 2.4 L will contain = 2.4/22.4 = 0.107 mole of SO2.

Therefore, 0.107 mole of SO2 is present in 2.4 L at STP.

Explanation:

To calculate [H3O+] in the solution we must first find the pH from the [ OH-]

That's

pH + pOH = 14

pH = 14 - pOH

To calculate the pOH we use the formula

pOH = - log [OH-]

And [OH-] = 5.5 × 10^-5 M

So we have

pOH = - log 5.5 × 10^ - 5

pOH = 4.26

Since we've found the pOH we can now find the pH

That's

pH = 14 - 4.26

pH = 9.74

Now we can find the concentration of H3O+ in the solution using the formula

pH = - log H3O+

9.74 = - log H3O+

Find the antilog of both sides

The solution is basic since it's pH lies in the basic region.

Hope this helps you

Answer:

The total photons required for this radiation = 5.1938 × 10²⁸ photons

Explanation:

Given that:

A microwave oven heats by radiating food with microwave radiation, which is absorbed by the food and converted to heat.

If the radiation wavelength is 12.5 cm,

density of water = 1g/cm³

volume of the container = 0.250 L = 250 cm³

density = mass/volume

mass of the water = density × volume

mass of the water =  1g/cm³  × 250 cm³

mass of the water = 250 g

specific heat capacity of water = 4.182 J/g°C

The change in temperature was from 20.0° C to 99° C

ΔT =( 99 -20.0)° C

ΔT = 79.0° C

The heat absorbed in the process is calculated by using the formula,

q = mcΔT

q = 250 g × 4.182 J/g°C ×  79.0° C

q = 82594.5 Joules

Recall that the radiation wavelength λ = 12.5 cm = 0.125 m

The amount of energy of one photon of the radiation wavelength is determined by using the formula:

E = hv  

since v = c/λ

E = hc/λ

where;

h = Planck's constant = 6.626 × 10⁻³⁴ J.s

c = velocity of light = 3.0 × 10⁸ m/s

∴

E = (6.626 × 10⁻³⁴ J.s × 3.0 × 10⁸ m/s)/ 0.125 m

E = 1.59024⁻²⁴ Joules

The total photons required for this radiation = total heat energy/energy of radiation

The total photons required for this radiation = 82594.5 Joules/1.59024⁻²⁴ Joules

The total photons required for this radiation = 5.1938 × 10²⁸ photons

Answer:

2.3 × 10⁻⁹

Explanation:

Step 1: Write the reaction for the solution of calcium oxalate

CaC₂O₄(s) ⇄ Ca²⁺(aq) + C₂O₄²⁻(aq)

Step 2: Make an ICE chart

We can relate the molar solubility (S) with the solubility product constant (Ksp) through an ICE chart.

        CaC₂O₄(s) ⇄ Ca²⁺(aq) + C₂O₄²⁻(aq)

I                                0                 0

C                              +S               +S

E                                S                 S

The solubility product constant is:

Ksp = [Ca²⁺] × [C₂O₄²⁻] = S² = (4.8 × 10⁻⁵)² = 2.3 × 10⁻⁹

Answer:

The mass of ammonium phosphate produced is 14.3g

Explanation:

Full question contains: "What mass of ammonium phosphate is produced by the reaction of 4.9g of ammonia"

Ammonium phosphate ((NH₄)₃PO₄) can be produced by the reaction of phosphoric acid (H₃PO₄) with ammonia (NH₃) as follows:

H₃PO₄ + 3NH₃ → (NH₄)₃PO₄

Where 1 mole of phosphoric acid reacts with 3 moles of ammonia producing 1 mole of ammonium phosphate.

To know how many grams of ammonium phosphate we need to find moles of ammonia that react, and, with the chemical equation we can find moles of ammonium phosphate and its mass as follows:

Moles ammonia (Molar mass: 17.031g/mol):

4.9g × (1mol / 17.031g) = 0.288 moles of ammonia you have in 4.9g

Moles of ammonium phosphate (149.09g/mol) and its mass:

As 0.288 moles of NH₃ are reacting and 3 moles of ammonia produce 1 mole of ammonium phosphate, moles produced are:

Moles (NH₄)₃PO₄:

0.288 moles NH₃ ₓ (1 mol (NH₄)₃PO₄  / 3 mol NH₃) = 0.0959 moles (NH₄)₃PO₄

These moles are, in grams:

0.0959 moles (NH₄)₃PO₄ ₓ (149.09g / mol) = 14.3g ammonium phosphate.

Answer:

CHC12

Explanation:

i am not really sure i am onna do a quick research 4 u tho

Answer:

[tex]91°C[/tex]

Explanation:

CHECK THE COMPLETE QUESTION BELOW;

Suppose that 0.95 g of water condenses on a 75.0 g block of iron that is initially at 22 °c. if the heat released during condensation is used only to warm the iron block, what is the final temperature (in °c) of the iron block? (assume a constant enthalpy of vaporization for water of 44.0 kj/mol.)

Heat capacity which is the amount of heat required to raise the temperature of an object or a substance by one degree

From the question, it was said that that 0.95 g of water condenses on the block thenwe know that Heat evolved during condensation is equal to the heat absorbed by iron block.

Then number of moles =given mass/ molecular mass

Molecular mass of water= 18 g/mol

Given mass= 0.95 g

( 0.95 g/18 g/mol)

= 0.053 moles

Then Heat evolved during condensation = moles of water x Latent heat of vaporization

Q= heat absorbed or released

H=enthalpy of vaporization for water

n= number of moles

Q=nΔH

Q = 0.053 moles x 44.0 kJ/mol

= 2.322 Kj

=2322J

We can now calculate Heat gained by Iron block

Q = mCΔT

m = mass of substance

c = specific heat capacity

=change in temperature

m = 75 g

c = 0.450 J/g/°C

If we substitute into the above formula we have

Q= 75 x 0.450 x ΔT

2322 = 75 x 0.450 x ΔT

ΔT = 68.8°C

Since we know the difference in temperature, we can calculate the final temperature

ΔT = T2 - T1

T1= Initial temperature = 22°C

T2= final temperature

ΔT= change in temperature

T2 = T1+ ΔT

= 68.8 + 22

= 90.8 °C

=91°C

Therefore, final temperature is [tex]91°C[/tex]

The final temperature of the iron block is 91∘C.

Given that;

Heat lost during condensation of the water = Heat gained by iron block

Mass of water(mw) = 0.95 g

Latent heat of vaporization =  Latent heat of condensation(L) = 44.0 kJ/mol

Mass of iron(mi) = 75.0 g

Initial temperature of iron(T1) =  22∘C

Final temperature of iron(T2) = ?

Heat capacity of iron(ci) =  0.449 J⋅g−1⋅∘C−1

So;

mwL = mici(T2 - T1)

Substituting values;

(0.95g/18g/mol) ×  44.0 × 10^3(J/mol) = 75.0(g) × 0.449 J⋅g−1⋅∘C−1 (T2 - 22∘C)

2322.2 = 33.7T2 - 741.4

2322.2 +  741.4 = 37.4T2

T2 = (2322.2 +  741.4)/ 33.7

T2 =91∘C

Missing parts;

Suppose that 0.95 g of water condenses on a 75.0 g block of iron that is initially at 22 °c. if the heat released during condensation is used only to warm the iron block, what is the final temperature (in °c) of the iron block? (assume a constant enthalpy of vaporization for water of 44.0 kj/mol.)

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Answer:

The gas is Methane at 340K

Answer:

The volume of the container is 59.112 L

Explanation:

Given that,

Number of moles of Oxygen, n = 3

Temperature of the gas, T = 300 K

Pressure of the gas, P = 1.25 atm

We need to find the volume of the container. For a gas, we know that,

PV = nRT

V is volume

R is gas constant, R =  0.0821 atm-L/mol-K

So,

[tex]V=\dfrac{nRT}{P}\\\\V=\dfrac{3\ mol\times 0.0821\ L-atm/mol-K \times 300\ K}{1.25\ atm}\\\\V=59.112\ L[/tex]

So, the volume of the container is 59.112 L

Answer:

[tex][F^-]_{max}=4x10{-3}\frac{molF^-}{L}[/tex]

Explanation:

Hello,

In this case, for the described situation, we infer that calcium reacts with fluoride ions to yield insoluble calcium fluoride as shown below:

[tex]Ca^{+2}(aq)+2F^-(aq)\rightleftharpoons CaF_2(s)[/tex]

Which is typically an equilibrium reaction, since calcium fluoride is able to come back to the ions. In such a way, since the maximum amount is computed via stoichiometry, we can see a 1:2 mole ratio between the ions, therefore, the required maximum amount of fluoride ions in the "hard" water (assuming no other ions) turns out:

[tex][F^-]_{max}=2.0x10^{-3}\frac{molCa^{2+}}{L}*\frac{2molF^-}{1molCa^{2+}} \\[/tex]

[tex][F^-]_{max}=4x10{-3}\frac{molF^-}{L}[/tex]

Best regards.

Answer:

THE MASS OF NITROGEN GAS IN THIS CONDITIONS IS 0.0589 g

Explanation:

In an ideal condition

PV = nRT or PV = MRT/ MM where:

M = mass = unknown

MM =molar mass = 28 g/mol

P = pressure = 2 atm

V = volume = 25 mL = 0.025 L

R = gas constant = 0.082 L atm/mol K

T = temperature = 290 K

n = number of moles

The gas in the question is nitrogen gas

Molar mass of nitrogen gas = 14 * 2 = 28 g/mol

Then equating the variables and solving for M, we have

M = PV MM/ RT

M = 2 * 0.025 * 28 / 0.082 * 290

M = 1.4 / 23.78

M = 0.0589 g

The mass of the nitrogen gas at ideal conditions of 2 atm, 25 mL volume and 290 K temperature is 0.0589 g

Answer:

-170.65

188.8+ 256.8-205.8-(2x205.2)

-170.65 is the entropy change.

Entropy trade is the phenomenon that is the measure of change of disorder or randomness in a thermodynamic gadget. It is associated with the conversion of heat or enthalpy completed in work. A thermodynamic device that has extra randomness means it has high entropy.

Subtract the sum of the absolute entropies of the reactants from the sum of the absolute entropies of the products, each extended by using their suitable stoichiometric coefficients, to reap ΔS° for the reaction.

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Answer:

The process will be spontaneous above 702 K.

Explanation:

Step 1: Given data

Step 2: Calculate the temperature range in which the process will be spontaneous

The reaction will be spontaneous when the standard Gibbs free energy (ΔG°) is negative. We can calculate ΔG° using the following expression.

ΔG° = ΔH° - T × ΔS°

When ΔG° < 0,

ΔH° - T × ΔS° < 0

ΔH° < T × ΔS°

T > ΔH°/ΔS°

T > (308,000 J/mol)/(439 J/mol.K)

T > 702 K

The process will be spontaneous above 702 K.

Answer:

Anaphase

Explanation:

The centromere splits during the anaphase of the cell division. Thus, allowing the two linked chromatids to separate.

A typical chromosome is made up of two sister chromatids joined together by a structure known as the centromere. During cell division - at the metaphase stage - the chromosomes align at the equator of the cell, forming the metaphase plate. The spindle from the opposing ends of the cell engages each chromosome at the kinetochore of the centromere.

At the anaphase stage, the centromere splits, leading to the separation of the sister chromatids of each chromosome. The sister chromatids of the same then start migrating in the opposite direction as a result of the shortening of the spindle fiber.

Answer:

+ small

Explanation:

The entropy is obtained from;

∆S= ∆H/T

Where;

∆S= entropy of the system

∆H= enthalpy if the system = +23.7 KJ

T= absolute temperature of the system = 390 K

∆S= 23.7 ×10^3/390 = 60.8 JK^-

There is a small positive change in entropy.

Answer:

ΔG°′ = 1.737 KJ/mol

Explanation:

The reaction involves the transfer of two electrons in the form of hydride ions from reduced coenzyme Q, CoQH₂ to fumarae to form succinate and oxidized coenzyme Q, CoQ.

The overall equation of reaction is as follows:

fumarate²⁻ + CoQH₂ ↽⇀ succinate²⁻ + CoQ ;    ΔE∘′=−0.009 V

Using the equation  for standard free energy change; ΔG°′ = −nFΔE°′

where n = 2; F = 96.5 KJ.V⁻¹.mol⁻¹; ΔE°′ = 0.009 V

ΔG°′ = - 2 * 96.5 KJ.V⁻¹.mol⁻¹ * 0.009 V

ΔG°′ = 1.737 KJ/mol

Answer:

NaN3 = 47.2 g

Explanation:

Given:

2 NaN3 ⇒ 2 Na  + 3 N2

Find:

Amount of NaN3

Computation:

N2 moles = Product of N2 / molar mass of N2

N2 moles =30.5/28

N2 moles = 1.0893

2NaN3 makes 3(N2 )

So,

NaN3 moles = (2/3) moles of N2  

NaN3 moles = ( 2/3) × 1.0893

NaN3 moles = = 0.7262

NaN3 mass = 0.7262 x 65

NaN3 = 47.2 g

Answer:

NaN3 = 47.2 g

Explanation:

Given:

2 NaN3 ⇒ 2 Na  + 3 N2

Find:

Amount of NaN3

Computation:

N2 moles = Product of N2 / molar mass of N2

N2 moles =30.5/28

N2 moles = 1.0893

2NaN3 makes 3(N2 )

So,

NaN3 moles = (2/3) moles of N2  

NaN3 moles = ( 2/3) × 1.0893

NaN3 moles = = 0.7262

NaN3 mass = 0.7262 x 65

NaN3 = 47.2 g

Explanation:

Answer:

The pH of the solution is 9.06.

Explanation:

The reaction of the dissociation of NH₃ in water is:

NH₃(aq) + H₂O(l)  ⇄  NH₄⁺(aq) + OH⁻(aq)     (1)

[NH₃] - x                     [NH₄⁺] + x     x  

The concentration of NH₃ and NH₄⁺ is:

[tex] [NH_{3}] = \frac{n_{NH_{3}}}{V_{T}} = \frac{C_{i}_{(NH_{3})}*Vi_{NH_{3}}}{V_{NH_{3}} + V_{NH_{4}^{+}}} = \frac{0.12 M*0.2 L}{0.2 L + 0.25 L} = 0.053 M [/tex]

[tex] [NH_{4}^{+}] = \frac{C_{i}_{(NH_{4}^{+})*V_{NH_{4}^{+}}}}{V_{NH_{3}} + V_{NH_{4}^{+}}} = \frac{0.15 M*0.25 L}{0.2 L + 0.25 L} = 0.083 M [/tex]

From equation (1) we have:

[tex]Kb = \frac{[NH_{4}^{+}][OH^{-}]}{[NH_{3}]}[/tex]

[tex] 1.8 \cdot 10^{-5} = \frac{(0.083 + x)*x}{0.053 - x} [/tex]

[tex] 1.8 \cdot 10^{-5}(0.053 - x) - (0.083 + x)*x = 0 [/tex]

By solving the above equation for x we have:

x =  1.15x10⁻⁵ = [OH⁻]

The pH of the solution is:

[tex] pOH = -log([OH^{-}]) = -log(1.15 \cdot 10^{-5}) = 4.94 [/tex]

[tex] pH = 14 - pOH = 14 - 4.94 = 9.06 [/tex]

Therefore, the pH of the solution is 9.06.

I hope it helps you!