If a substance has a half-life of 55.6 s, and if 230.0 g of the substance are present initially, how many grams will remain after 10.0 minutes?

Answer:

The edge length of a face-centered cubic unit cell is 435.6 pm.

Explanation:

In a face-centered cubic unit cell, each of the eight corners is occupied by one atom and each of the six faces is occupied by a single atom.

Hence, the number of atoms in an FCC unit cell is:

[tex] 8*\frac{1}{8} + 6*\frac{1}{2} = 4 atoms [/tex]

In a face-centered cubic unit cell, to find the edge length we need to use Pythagorean Theorem:

[tex] a^{2} + a^{2} = (4R)^{2} [/tex]     (1)

Where:

a: is the edge length

R: is the radius of each atom = 154 pm      

By solving equation (1) for "a" we have:

[tex] a = 2R\sqrt{2} = 2*154 pm*\sqrt{2} = 435.6 pm [/tex]    

Therefore, the edge length of a face-centered cubic unit cell is 435.6 pm.   

I hope it helps you!

Answer:

494.49 g of NaCl.

Explanation:

Data obtained from the question include the following:

Molality of NaCl = 3.140 m

Mass of water = 2.692 kg

Mass of NaCl =.?

Next, we shall determine the number of mole of NaCl in the solution.

Molality is simply defined as the mole of solute per unit kilogram of solvent. Mathematically, it is expressed as

Molality = mole of solute /Kg of solvent

With the above formula, we can obtain the number of mole NaCl in the solution as follow:

Molality of NaCl = 3.140 m

Mass of water = 2.692 kg

Mole of NaCl =..?

Molality = mole of solute /Kg of solvent

3.140 = mole of NaCl /2.692

Cross multiply

Mole of NaCl = 3.140 x 2.692

Mole of NaCl = 8.45288 moles

Finally, we shall covert 8.45288 moles of NaCl to grams. This can be obtained as follow:

Mole of NaCl = 8.45288 moles

Molar mass of NaCl = 23 + 35.5 = 58.5 g/mol

Mass of NaCl =.?

Mole = mass /Molar mass

8.45288 = mass of NaCl /58.5

Cross multiply

Mass of NaCl = 8.45288 × 58.5

Mass of NaCl = 494.49 g.

Therefore, 494.49 g of NaCl are present in the solution.

The mass of NaCl in 3.140 molal NaCl solution has been 494.493 grams.

Molality can be defined as the mass of solute present in 1000 grams of solvent.

Molality = [tex]\rm \dfrac{moles\;of\;solute}{mass\;of\;solvent\;(kg)}[/tex]

The moles of NaCl has been calculated as;

3.140 = [tex]\rm \dfrac{moles\;of\;NaCl}{mass\;of\;water\;(kg)}[/tex]

3.140 = [tex]\rm \dfrac{moles\;of\;NaCl}{2.692\;kg}[/tex]

Moles of NaCl = 3.140 [tex]\times[/tex] 2.692

Moles of NaCl = 8.45288 mol

The moles can be expressed as;

Moles = [tex]\rm \dfrac{weight}{molecular\;weight}[/tex]

Molecular weight of NaCl = 58.5 g/mol

The mass of NaCl can be calculated as:

8.45288 mol = [tex]\rm \dfrac{mass\;of\;NaCl}{58.5\;g/mol}[/tex]

Mass of NaCl = 58.5 g/mol [tex]\times[/tex] 8.45288 mol

Mass of NaCl = 494.493 grams.

The mass of NaCl in 3.140 molal NaCl solution has been 494.493 grams.

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Answer:

the answer is 2,000 nickels.

Explanation:

we multiplied 100 by 100, because there are 100 cents in a dollar, and we divided 10,000 by 5, because there are 5 cents in a nickel.

Answer:

Two constitutional isomers for the compound C3H8S are shown in the attachment below

Explanation:

Constitutional isomers are isomers that have the same molecular formula but different connectivity. Two constitutional isomers for the compound C3H8S are shown in the attachment below.

As per the concept of structural isomers, the  two constitutional isomers that share the molecular formula C₃H₈S are attached in attachment below.

Structural isomers are defined as the isomers  in which atoms are completely  arranged  in a different order but the molecular formula remains the same.

They are the molecules which have same molecular formula but different  connectivities  of atoms  which depend on the order they are put together. An increase in the number of carbon atoms leads to an increase  in the structural isomers.

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Answer:

The reaction given is:

In (g) + H₂ (g) ⇔ InH₂ (g), the Kp is 1.48 at 973 K.

The partial pressures measured in the reaction vessel is Partial pressure of In is 0.0540 atm, partial pressure of H₂ is 0.0250 atm, and the partial pressure of InH₂ is 0.0780 atm. By using the table given in the attachment below, the value of PInH₂ is (0.078-x), PIn is (0.054 + x), and the value of PH2 is (0.025 + x).

Kp = PInH₂/PIn × PH₂ = (0.078 - x) / (0.054 +x) (0.025 + x)

1.48 = (0.078 - x) / (0.054 +x) (0.025 + x)

x = 0.06689

Now the partial pressures of In, H₂ and InH₂ will be,

PH₂ = 0.025 + x = 0.025 + 0.0668 = 0.0918 atm

PIn = 0.054 + 0.0668 = 0.1208 atm

PInH₂ = 0.078 - 0.0668 = 0.0112 atm

Now the Qp or the reaction quotient will be,

Qp = (0.078) / (0.054) (0.025) = 57.78.

Answer:

1)In organic chemistry, the bromine test is a qualitative test for the presence of unsaturation (carbon-to-carbon double or triple bonds), phenols and anilines. ... The more unsaturated an unknown is, the more bromine it reacts with, and the less coloured the solution will appear.

2)The equation for incomplete combustion of propane is: 2 C3H8 + 9 O2 → 4 CO2 + 2 CO + 8 H2O + Heat. If not enough oxygen is present for complete combustion, incomplete combustion occurs. The result of incomplete combustion is, once again, water vapour, carbon dioxide and heat. But it also produces carbon monoxide.

Explanation:

3)Propene, also known as propylene, is an unsaturated organic compound with the chemical formula {\displaystyle {\ce {CH3CH=CH2}}}. It has one double bond, and is the second simplest member of the alkene class of hydrocarbons. It is a colorless gas with a faint petroleum-like odor. 

Formula: C3H6

IUPAC ID: Propene

4)Margarines are chemically created during hydrogenation which, until January 1, 2006, relied upon trans fats to solidify their vegetable oils. Food companies have been exploring options for replacing trans fat in partially hydrogenated margarine.

Answer:

0.05 mole of Br2.

Explanation:

We'll begin by writing the balanced equation for the reaction. This is given below:

C2H4 + Br2 —› C2H4Br2

From the balanced equation above,

1 mole of C2H4 reacted with 1 mole of Br2 to produce 1 mole of C2H4 Br2.

Finally, we shall determine the number of moles bromine that will react with 0.05 mole of C2H2.

The number of mole of Br2 needed for the reaction can be obtained as follow:

From the balanced equation above,

1 mole of C2H4 reacted with 1 mole of Br2.

Therefore, 0.05 mole of C2H4 will also react with 0.05 mole of Br2.

Therefore, 0.05 mole of Br2 is needed for the reaction.

Answer:

3.11

Explanation:

Any buffer system can be described with the reaction:

[tex]HA~->~H^+~+~A^-[/tex]

Where is the acid and is the base. Additionally, the calculation of the pH of any buffer system can be made with the Henderson-Hasselbach equation:

[tex]pH~=~pKa~+~Log(\frac{ [A^-]}{[HA]})[/tex]

With all this in mind, we can write the reaction for our buffer system:

-) Nitrous acid: [tex]HNO_2[/tex]

-) Sodium nitrate: [tex]NaNO_2[/tex]

[tex]HNO_2~->~H^+~+~NO_2^-[/tex]

In this case, the acid is [tex]HNO_2[/tex] with a concentration of 0.150 M and a volume of 45.0 mL (0.045 L). The base is [tex]NO_2^-[/tex] with a concentration of 0.175 M and a volume of 20.0 mL (0.020 L).

We can calculate the moles of each compound is we take into account the molarity equation ([tex]M=\frac{mol}{L}[/tex]). So:

-) moles of [tex]HNO_2[/tex]:

[tex]mol=0.150~M*0.045~L=0.00657[/tex]

-) moles of [tex]NO_2^-[/tex]:

[tex]mol=0.175~M*0.020~L=0.0035[/tex]

The total volume would be:

0.020 L + 0.045 L = 0.065 L

With this in mind, we can calculate the molarity of each compound:

-) Concentration of [tex]HNO_2[/tex]

[tex]M=\frac{0.00657~mol}{0.065~L}=0.101~M[/tex]

-) Concentration of [tex]NO_2^-[/tex]

[tex]M=\frac{0.0035~mol}{0.065~L}=0.0538~M[/tex]

The pKa reported is 3.39, therefore we can plug the values into the Henderson-Hasselbach equation:

[tex]pH~=~3.39~+~Log(\frac{[0.0538~M]}{[0.101~M]})~=~3.11[/tex]

The final pH value would be 3.11

I hope it helps!

The pH of a buffer made by combining 45.0 mL of 0.150M nitrous acid and 20.0mL of 0.175M sodium nitrate is 2.87.

We have a buffer made by combining 45.0mL of 0.150 M nitrous acid and 20.0mL of 0.175M sodium nitrate.

Nitrous acid is a weak acid and nitrate ion is its conjugate base.

It is a solution used to resist abrupt changes in pH when acids or bases are added.

We do so by multiplying the molar concentration by the volume in liters.

HNO₂: 0.150 mol/L × 0.0450 L = 6.75 × 10⁻³ mol

NaNO₂: 0.175 mol/L × 0.0200 L = 3.50 × 10⁻³ mol

The total volume will be the sum of the volumes of each solution.

V = 45.0 mL + 20.0 mL = 65.0 mL = 0.0650 L

HNO₂: 6.75 × 10⁻³ mol/0.0650 L = 0.104 M

NaNO₂: 3.50 × 10⁻³ mol/0.0650 L = 0.0538 M

We can calculate the pH of a buffer system using Henderson-Hasselbach's equation.

pH = pKa + log [NaNO₂]/[HNO₂]

pH = 3.16 + log 0.0538/0.104 = 2.87

The pH of a buffer made by combining 45.0 mL of 0.150M nitrous acid and 20.0mL of 0.175M sodium nitrate is 2.87.

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Answer:

Explanation:

True

Answer:

There are no forces holding the gas particles together.

Explanation:

Answer:

The rms speed of its molecules becomes. (T) has become four times. Therefore, v_(rms) will become two times,...

Answer: Gamma Radiation

Explanation:

The emission of Gamma rays does not cause a change in both the atomic and mass number. They are  electromagnetic radiation.

The radiations that leaves without changing the atomic mass and atomic number of the particle have been gamma radiations. Thus, option D is correct.

Radiations have been the energy that has been evolved by the particles during energy transitions. The nuclear decay results with the release of the energy from the particle resulting in the change in the atomic mass.

The electromagnetic radiations have been capable of emitting the radiation without changing the mass and atomic number of the element. The gamma radiations have been the electromagnetic radiations. Thus, option D is correct.

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Answer:

PbCl₂ will precipitate from solution.

Explanation:

Statements are:

Insufficient information is given.

Both NH4NO3 and PbCl2 precipitate from solution.

No precipitate forms.

PbCl2 will precipitate from solution.

NH4NO3 will precipitate from solution.

The reaction of ammonium chloride (NH₄Cl) with lead nitrate (Pb(NO₃)₂) is:

Pb(NO₃)₂ + 2NH₄Cl → PbCl₂ + 2 NH₄NO₃

Talking of rules of solubility, all nitrates are soluble in water, that means NH₄NO₃ is soluble and no precipitate is formed.

In the same way, all chlorides are soluble except silver chloride and lead chloride. That means:

Answer:

[tex]\huge\boxed{Density}[/tex]

Explanation:

This is because of density. Since Ice is less dense than water, the ice even formed inside the pond then starts floating on the surface of water. Because of this density, Ice floats on water and thus the water freezes at the surface.

Answer:

Density

Explanation:

Water is less dense as a solid than as a liquid, so as ponds freeze, the ice floats at the top and the pond freezes from the top-down.

Answer:

A

Explanation:

The change in entropy for the surroundings in a situation where heat flows from a hotter system to a cooler surrounding is Greater than Zero.

Here the randomness of the molecules increase as the temperature of the surrounding increases.( it absorbs heat from the system).

Answer:

Option a (Greater than zero) is the correct answer.

Explanation:

Some other three choices don't apply to either the situations in question. And the correct approach will be Options A.

Answer:

D) 65.7%

Explanation:

Based on the reaction:

2H2(g)+O2(g)⟶2H2O(l)

2 moles of hydrogen produce 2 moles of water assuming an excess of oxygen.

To find percent yield of the reaction we need to find theoretical yield (The yield assuming all hydrogen reacts producing water). With theoretical yield and actual yield (32.8g H₂O) we can determine percent yield as 100 times the ratio between actual yield and theoretical yield.

Theoretical yield:

Moles of 5.58g H₂:

5.58g H₂ ₓ (1 mol / 2.016g) = 2.768 moles H₂

As 2 moles of H₂ produce 2 moles of H₂O, if all hydrogen reacts will produce 2.768 moles H₂O. In grams:

2.768 moles H₂O ₓ (18.015g / mol) =

49.86g H₂O is theoretical yield

Percent yield:

Percent yield = Actual yield / Theoretical yield ₓ 100

32.8g H₂O / 49.86g ₓ 100 =

65.7% is percent yield of the reaction

Answer:

A. NaHCO₃

Explanation:

NaHCO₃ ⇒ NaOH + H₂CO₃

NaOH is a strong base and H₂CO₃ is a weak acid. Therefore, NaHCO₃ is a salt of a strong base-weak acid reaction. The salt is basic because carbonic acid (H₂CO₃) is a weak acid so it remains undissociated. So, there is a presence of additional OH⁻ ions that makes the solution basic.

Hope that helps.

The percentage strength of the agent is 10 %

Since 100 mL of a pharmaceutical preparation contains 20 mL of a 50% w/v solution of benzalkonium chloride, we desire to find the percentage strength of that agent in the 100 mL solution.

Let C₁ = percentage strength of 20 mL solution = 50 %, V₁ = initial volume = 20 mL, C₂ = percentage strength of agent in 100 mL solution and V₂ = final volume = 100 mL.

Since the initial quantity of agent in 20 mL solution equals the final quantity of agent in 100 mL solution, we have that

C₁V₁ = C₂V₂

So, making C₂ = percentage strength of agent in 100 mL solution the subject of the formula, we have

C₂ = C₁V₁/V₂

Substituting the values of the variables into the equation, we have

C₂ = C₁V₁/V₂

C₂ = 50 % × 20 mL/100 mL

C₂ = 50 % × 0.2

C₂ = 10 %

So, the percentage strength of the agent is 10 %.

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Answer: The question is not clear

Explanation:

a) A polyfunctional acid is an acid that has more than one functional group.

b) The equations of dissociation of phosphoric acid are:    

c) The equation for calculating the concentration of H₃O⁺ is [tex] [H_{3}O^{+}] = (\frac{K_{1}K_{2}K_{3}[H_{3}PO_{4}]}{[PO_{4}^{-3}]})^{1/3} [/tex]

a) A polyfunctional acid can be defined as an acid that has more than one functional group. Phosphoric acid (H₃PO₄) is an example of polyfunctional acid since it is composed of three hydroxyl groups joined to a phosphorus atom, which is also joined to an oxygen atom by a double bound. In that structure, the three hydrogen atoms of the hydroxyl groups give the acidic behavior to this compound.                  

b) Phosphoric acid has three equations of dissociation:  

The dissociation constants for the three above equations are:

[tex] K_{1} = \frac{[H_{2}PO_{4}^{-}][H_{3}O^{+}]}{[H_{3}PO_{4}]} [/tex]   (4)

[tex] K_{2} = \frac{[HPO_{4}^{2-}][H_{3}O^{+}]}{[H_{2}PO_{4}^{-}]} [/tex]    (5)

[tex] K_{3} = \frac{[PO_{4}^{3-}][H_{3}O^{+}]}{[HPO_{4}^{2-}]} [/tex]    (6)

c) We can calculate the concentration of H₃O⁺ for each equilibrium with the equations (4), (5), and (6).    

The general reaction of dissociation of phosphoric acid is given by the sum of equations (1), (2), and (3):

H₃PO₄ + 3H₂O ⇄ PO₄³⁻ + 3H₃O⁺   (7)  

The concentration of H₃O⁺ for the total dissociation reaction (eq 7) can be found as follows:  

[tex] K_{t} = \frac{[PO_{4}^{-3}][H_{3}O^{+}]^{3}}{[H_{3}PO_{4}]} [/tex]   (8)

Where:

[tex] K_{t} = K_{1}*K_{2}*K_{3} [/tex]

Hence, by knowing the dissociation constants K₁, K₂ and K₃, and the concentrations of PO₄³⁻ and H₃PO₄, the [H₃O⁺] is:

[tex][H_{3}O^{+}] = (\frac{K_{1}K_{2}K_{3}[H_{3}PO_{4}]}{[PO_{4}^{-3}]})^{1/3}[/tex]

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Answer:

The balanced chemical reaction is given as:

[tex]Cs_2SO_4(aq)+Ba(ClO_4)_2(aq)\rightarrow BaSO_4(s)+2CsClO_4(aq)[/tex]

Explanation:

When aqueous cesium sulfate and aqueous barium perchlorate are mixed together it gives white precipitate barium sulfate and aqueous solution od cesium perchlorate.

The balanced chemical reaction is given as:

[tex]Cs_2SO_4(aq)+Ba(ClO_4)_2(aq)\rightarrow BaSO_4(s)+2CsClO_4(aq)[/tex]

According to reaction, 1 mole of cesium sulfate reacts with 1 mole of barium perchlorate to give 1 mole of a white precipitate of barium sulfate and 2 moles of cesium perchlorate.

Answer:

a. the Kb of NO₂⁻ to find the hydroxide concentration.

Explanation:

When sodium nitrite is dissolved in water, it dissociates in sodium cation and nitrite anion according to the following equation.

NaNO₂(s) ⇒ Na⁺(aq) + NO₂⁻(aq)

Na⁺ comes from NaOH (strong base) so it doesn't react with water.

NO₂⁻ comes from HNO₂ (weak acid) so it reacts with water according to the following equation.

NO₂⁻(aq) + H₂O(l) ⇄ HNO₂(aq) + OH⁻(aq)

This is the basic reaction of nitrite ion, so we need the Kb of NO₂⁻ to  find the hydroxide concentration.

Answer:

8 CO₂(g)

Explanation:

just took the exam

Answer:

105/22*(1.251-0.620)

105/22*0.631

4.772*0.631

3.011132

Hope it helps

Answer:

3.0

Explanation:

First, complete the operations inside the parenthesis according to the normal rules for significant figures. Because there are subsequent calculations, keep at least one extra significant figure when possible: (4.7727) × (0.631).

The final product will be rounded to two significant figures because it can’t be more precise than the least precise number in the problem, 22. The final product is 3.0.

Answer:

They get more energy, so they vibrate!

Explanation:

Answer:

1229.08975 kPa

Explanation:

Given that:

The depth of the water = 100 m below the surface of the water.

The density of the water = 1150 kgm

The mass of the water = depth of the water × density of the water

The mass of the water = 100 m × 1150 kgm

The mass of the water = 115000 kgf/m²

The mass of the water is the pressure of the water at a depth of 100 m below the surface of the water.

Since 1 kgf/m² = 0.00980665 kPa

Then  115000 kgm² = (115000  ×  0.00980665) kPa

=  1127.76475 kPa

At standard temperature and pressure , the atmospheric pressure = 101.325 kPa.

Therefore, the pressure below the surface of sea water  = 1127.76475 kPa +   101.325 kPa

= 1229.08975 kPa

Answer: NaCl would give the higher pressure

Explanation:

Osmotic pressure depends only on the number of ions.

NaCl dissociates as Na+ and Cl- ; CsBr  dissociates as Cs+ and Br-

But the concentration of the solutions are different.  

Concentration (morality ) of NaCl = Moles /Litre = (1 g /58.44g/mol)/0.01L

Total number of ions in NaCl solution = 2 x (1 g /58.44g/mol)/0.01L ( 1 mol NaCl gives 2 moles ions, 1 mol Na+ and 1 mol Cl-)  

= 1.71×2RT

Similarly total number of ions in CsBr solution = 2 x (1 g /212.80 g/mol)/0.01L

= 0.47×2RT

Therefore osmotic pressure is higher in NaCl solution.

Answer:

Underneath the frozen upper layer, the water remains in its liquid form and does not freeze. Also, oxygen is trapped beneath the layer of ice. As a result, fish and other aquatic animals find it possible to live comfortably in the frozen lakes and ponds. ... This irregular expansion of water is called anomalous expansion.

Explanation:

so pretty much its because there is water under the top frozen layer and air is trapped underneath the ice

Answer:

PBr3 is NOT hypervalent

Explanation:

The molecule that is not hypervalent is PBr3

A molecule can be defined as the smallest part of a substance that can exist independently.

It is formed by the chemical combination of two or more atoms.

A molecule is said to be hypervalent when more than four pairs of electrons are around the central atom.

A molecule is said to be hypovalent when less than four pairs of electrons are around the central atom.

From the question, the molecule that is hypovalent is PBr3

This is because, phosphorus can make hypervalent compounds, but in this specific example it is sharing three bonds and has one lone pair, so it has simply a full octet.

Therefore, the molecule that is not hypervalent is PBr3.

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Answer:

the answer is 5.83x1020 molecules

Explanation:

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