Which of the following isotopes of chlorine has 16 neutrons in its nucleus?
33Cl
38Cl
42Cl

Answer:

6.941 grams

Explanation:

The molecular formula for Lithium is Li. The Si base unit for amount of substance is mole. 1 mole is equal to 1 moles Lithium, or 6.941 grams

Answer:

9.647989999999998

Explanation:

Answer:

0.27 g

Explanation:

The reaction equation:

[tex]Na_{2} CO_{3} + CaCl_{2}[/tex] → [tex]2NaCl + CaCO_{3}[/tex]

106g of Na2CO3 - 1 mole

0.5g of Na2CO3 = 0.5 ÷ 106

= 0.0047 moles.

1 mole of NaCl - 58.5

⇒ 0.0047 moles = 0.0047 × 58.5

= 0.27g.

When 0.5 grams of Na₂CO₃ react with excess CaCl₂, 0.6 g of NaCl are formed.

We combine 0.5 grams of Na₂CO₃ with excess CaCl₂ and we want to know the mass of NaCl produced. This is a stoichiometry problem.

Stoichiometry refers to the relationship between the quantities of reactants and products before, during, and following chemical reactions.

First, we will write the balanced chemical equation.

Na₂CO₃ + CaCl₂ ⇒ 2 NaCl + CaCO₃

We will consider the following relationships.

[tex]0.5 g Na_2CO_3 \times \frac{1molNa_2CO_3}{105.99gNa_2CO_3} \times \frac{2molNaCl}{1molNa_2CO_3} \times \frac{58.44gNaCl}{1molNaCl} = 0.6gNaCl[/tex]

When 0.5 grams of Na₂CO₃ react with excess CaCl₂, 0.6 g of NaCl are formed.

Learn more about stoichiometry here: https://brainly.com/question/9743981

Answer: Provided in the explanation section

Explanation:

Our questions says that:

It is usually assumed that an action potential begins immediately at the cathode. If this were true, both methods for calculating conduction velocity would provide the same answer. However, when a strong stimulus intensity is used, the action potential may begin some distance away from the cathode. Under these conditions, the difference method would be more accurate.Did you observe any important difference between the conduction velocity values?

Answer to this :

By using the difference method, you subtract out any "uncertainties" involved in the measurement of latencies. Say for example, saw we are uncertain as to where the AP's are actually originating within the vicinity of the stimulating electrodes, this "error" will be introduced into both latency measurements, and therefore subtracted out when performing a difference method calculation.

However, the difference method is only experimentally sound when one is dealing with the same population of nerve fibres over the recording electrodes used, which is not the case with the sciatic nerve, as it is a short nerve, and thin at one end.

    The non-uniformity of the nerve, and the difficulty in making accurate measurements of very small distances and latencies are principal points to consider when making conduction velocity measurements. Naturally if the nerve studied were longer and more uniform, we would improve the accuracy of our calculations.

cheers i hope this helped !!!!

Answer:

15g

Explanation:

Molar mass of acetic acid = 60g/mol

Molarity = mass ÷ molar mass

mass = 0.25 × 60

= 15g

∴ 15g of acetic acid weighed into 1L volumetric flask would give 0.25M  of acetic acid.

Alternatively, if the solution is being prepared from a stock solution of known concentration, (say 500mL of 0.5M solution), the formular C2V1 =C2V2 can be used to find the dilution volume.

Answer: B. It exposes more of the solute to the water molecules.

Explanation:

Rate of a reaction is dependent on following factors:

a) adding a catalyst: Adding a catalyst increases the rate of reaction

b) reducing the surface area: The rate of the reaction will decrease by reducing the surface area

c) raising the temperature: Increasing the temperature increases the rate of the reaction.

d) increasing the amount of reactants : Increasing the amount of reactants increases the rate of reaction.

If the reactants are present in smaller size, more reactants can react as decreasing the size increases the surface area of the reactants which will enhance the contact of molecules. Hence, more products will form leading to increased rate of reaction.

Thus reducing solute particle size increase the speed at which the solute dissolves in water by exposing more of the solute to the water molecules.

Answer:

B. It exposes more of the solute to the water molecules.

Answer:

The value of Kc C. remains the same.

The value of Qc C. is less than Kc.

The reaction must: A. run in the forward direction to reestablish equilibrium

The number of moles of Cl2 will  B. decrease.

Explanation:

Le Chatelier's Principle states that if a system in equilibrium undergoes a change in conditions, it will move to a new position in order to counteract the effect that disturbed it and recover the state of equilibrium.

A decrease in volume causes the system to evolve in the direction in which there is less volume, that is, where the number of gaseous moles is less.

But temperature is the only variable that, in addition to influencing equilibrium, modifies the value of the constant Kc. So if the volume of the equilibrium system is suddenly decreased at constant temperature: The value of Kc remains the same.

As mentioned, if the volume of an equilibrium gas system decreases, the system moves to where there are fewer moles. In this case, being:

PCl₃(g) + Cl₂(g) ⇔ PCl₅(g)

The equilibrium in this case then shifts to the right because there is 1 mole in the term on the right, compared to the two moles on the left. So, The reaction must: A. run in the forward direction to reestablish equilibrium.

By decreasing the volume, and so that Kc remains constant, being:

[tex]Kc=\frac{[PCl_{5} ]}{[PCl_{3}]*[Cl_{2} ]}=\frac{\frac{nPCl_{5} }{Volume} }{\frac{nPCl_{3}}{Volume}*\frac{nCl_{2} }{Volume} } =\frac{nPCl_{5}}{nPCl_{3}*nCl_{2}} *Volume[/tex]

 where nPCl₅, nPCl₃ and nCl₂ are the moles in equilibrium of PCl₅, PCl₃ and Cl₂

so,  the number of moles of Cl₂ should decrease.The number of moles of Cl2 will  B. decrease.

If the reaction quotient is less than the equilibrium constant, Qc <Kc, the system will evolve to the right, the direct reaction prevailing, to increase the concentration of products. So in this case, if the reaction moves to the right, the value of Qc C. is less than Kc.

Answer:

I, II, and III

Explanation:

In the titration of NH₃ with HCl:

NH₃ + HCl → NH₄⁺ + Cl⁻

Where NH₃ is the weak base and NH₄⁺ is the conjugate acid.

I: At 0 L HCl, pH would be calculated based on the concentration and Kb of the weak base: At 0L of HCl, you will have just NH₃ in solution. That means you would calculate the pH just from the concentration of the weak base using Kb. That means I is true.

II: At 1 L HCl, pH would be calculated based on the concentration and Ka of the conjugate acid: When you add 1L of HCl, you will have in solution just NH₄⁺, the conjugate acid. That means you would calculate the pH of the solution just with the Ka of the conjugate acid and its concentration. II is true.

III: At 2 L HCl, pH would be calculated based on the concentration of excess acid in solution: At 2L of HCl solution, you have HCl in excess in the solution. As HCl is a strong acid, the pH would be affected in the big way by this concentration in excess. III is true.

Answer:65N

Explanation:75-10=65

100-100=0

Therefore=65n

Answer:

the answer is 65N

Answer:

14 moles

Explanation:

For an Ideal gas,

PV = nRT...................... Equation 1

Where P = Pressure, V = Volume, n = number of mole, R = Molar gas constant.

make n the subject of the equation

n = PV/RT.................. Equation 2

Given: P = 14.297 atm, V = 22.9 L = 22.9 dm³, T = 12 °C = (12+273) K = 285 K.

Constant: R = 0.082 atm.dm³/K.mol

Substitute these values into equation 2

n = (14.297×22.9)/(285×0.082)

n = 327.4013/23.37

n = 14.009

n ≈ 14 moles

Answer:

1.02 × 10³ g

Explanation:

Step 1: Write the balanced equation

2 CaCO₃ + H₂SO₄ ⇒ CO₂ + H₂O + CaSO₄

Step 2: Calculate the moles corresponding to 500 g of sulfuric acid

The molar mass of sulfuric acid is 98.08 g/mol.

[tex]500g \times \frac{1mol}{98.08g} = 5.10mol[/tex]

Step 3: Calculate the moles of calcium carbonate that react with 5.10 moles of sulfuric acid

The molar ratio of CaCO₃ to H₂SO₄ is 2:1. The moles that react of calcium carbonate are (2/1) × 5.10 mol = 10.2 mol

Step 4: Calculate the mass corresponding to 10.2 moles of calcium carbonate

The molar mass of calcium carbonate is 100.09 g/mol.

[tex]10.2mol \times \frac{100.09 g}{mol} =1.02 \times 10^{3} g[/tex]

Answer:

C. The energy of motion

Explanation:

Kinetic energy is the energy associated with the movement of objects.

The kinetic energy of an object depends on both its mass and velocity, with its velocity playing a much greater role.

Example of Kinetic Energy:

1. An airplane has a large amount of kinetic energy in flight due to its large mass and fast velocity.

// have a great day //

Kinetic energy is the energy of motion.

So kinetic energy is present when objects move.

For example, a snowball rolling down a mountain.

Answer:

32 K is approx. -241.15° C

Answer:

[HI] = 0.5239M

[H₂] = 7.05x10⁻²

[I₂] = 7.05x10⁻²

Explanation:

The reaction of HI to produce H₂ and I₂ is:

2HI → H₂ + I₂

Where K of reaction is defined as:

K = [H₂] [I₂] / [HI]²

Replacing with the concentrations of the gases in equilibrium:

K = [4.34x10⁻²] [4.34x10⁻²] / [0.323] ²

K = 0.0181

If you add 0.228 mol = 0.228M (Because volume of the flask is 1.0L), the concentration when the system reaches the equilibrium are:

[HI] = 0.228M + 0.323M - X = 0.551M - X

[H₂] = 4.34x10⁻² + X

[I₂] = 4.34x10⁻² + X

Where X is reaction coordinate.

Replacing in K formula:

K = 0.0181 = [4.34x10⁻²+ X] [4.34x10⁻²+ X] / [0.551 - X] ²

0.0181 =  0.00188356 + 0.0868 X + X² / 0.303601 - 1.102 X + X²

0.005495 - 0.01995 + 0.0181X² = 0.00188356 + 0.0868 X + X²

0 = -0.003611 + 0.10675X + 0.9819X²

Solving for X:

X = -0.136 → False solution, there is no negative concentrations.

X = 0.0271 → Right solution.

Replacing for concentrations of each species:

Answer:

[tex]Purity=99\%[/tex]

Explanation:

Hello,

In this case, the undergoing precipitation reaction is:

[tex]MgCl_2+2AgNO_3\rightarrow Mg(NO_3)_2+2AgCl[/tex]

Thus, for the 0.2500 moles of silver nitrate, the following mass of magnesium chloride is consumed (consider their 2:1 molar ratio):

[tex]m_{MgCl_2}=0.2500molAgNO_3*\frac{1molMgCl_2}{2molAgNO_3} *\frac{95.2gMgCl_2}{1molMgCl_2} \\\\m_{MgCl_2}=11.90gMgCl_2[/tex]

Therefore, the purity of the sample is:

[tex]Purity=\frac{11.90g}{12.00g}*100\%\\ \\Purity=99\%[/tex]

Best regards.

Answer: 99. 17%

Explanation:

MgCl2(aq)+2AgNO3(aq)⟶2AgCl(s)+Mg(NO3)2(aq)

(0.2500 mol AgNO3 × 1 mol (MgCl2) /2 mol (AgNO3) × 95.211 g MgCl2 /1 mol MgCl2)

divided by 12.00 g sample = 0.99178 X 100 ≈ 99.18%

Answer:

1. Methyl ethanoate i.e CH3COOCH3

2. Methyl butanoate i.e CH3CH2CH2COOCH3

Explanation:

The reaction between an organic acid and alcohol is called esterification in which an ester is formed along side with water.

Thus, the name ester formed can be obtained as follow:

1. Reaction of acetic acid, CH3COOH with methanol, CH3OH.

CH3COOH + HOCH3 –> CH3COOCH3 + H2O

The name of the ester formed is methyl ethanoate i.e CH3COOCH3

2. Reaction of butanoic acid, CH3CH2CH2COOH with methanol, CH3OH.

CH3CH2CH2COOH + HOCH3 —> CH3CH2CH2COOCH3 + H2O

The name of the ester formed is methyl butanoate i.e CH3CH2CH2COOCH3

Answer:

I think it's D. 300(g) + Fe2O3(s)

Answer:

matter, dense, equal

Explanation:

According to Rutherford's nuclear theory, the core of an atom (nucleus) contains most of the matter of an atom and is dense, so the majority of the mass of a fluorine atom cannot be due to its nine electrons. According to Rutherford's nuclear theory, most of the volume of an atom is empty space, so the volume of a hydrogen atom cannot be mostly due to the proton. According to Rutherford's nuclear theory, the number of negatively charged particles outside the nucleus is equal the number of positively charged particles within the nucleus, so a nitrogen atom has 7 protons and 7 electrons, while a phosphorous atom cannot have 15 protons and 150 electrons.

Answer:

2.05*10⁻⁵ moles of CF₂ can dissolve in 100 g of water.

12.82 moles of CaF₂ will dissolve in exactly 1.00 L of solution

Explanation:

First, by definition of solubility, in 100 g of water there are 0.0016 g of CaF₂. So, to know how many moles are 0.0016 g, you must know the molar mass of the compound. For that you know:

So the molar mass of CaF₂ is:

CaF₂= 40 g/mole + 2*19 g/mole= 78 g/mole

Now you can apply the following rule of three: if there are 78 grams of CaF₂ in 1 mole, in 0.0016 grams of the compound how many moles are there?

[tex]moles=\frac{0.0016 grams*1 mole}{78 grams}[/tex]

moles=2.05*10⁻⁵

2.05*10⁻⁵ moles of CF₂ can dissolve in 100 g of water.

Now, to answer the following question, you can apply the following rule of three: if by definition of density in 1 mL there is 1 g of CaF₂, in 1000 mL (where 1L = 1000mL) how much mass of the compound is there?

[tex]mass of CaF_{2}=\frac{1000 mL*1g}{1mL}[/tex]

mass of CaF₂= 1000 g

Now you can apply the following rule of three: if there are 78 grams of CaF₂ in 1 mole, in 1000 grams of the compound how many moles are there?

[tex]moles=\frac{1000 grams*1 mole}{78 grams}[/tex]

moles=12.82

12.82 moles of CaF₂ will dissolve in exactly 1.00 L of solution

Answer:

Option f: an addition of HCl will exceed the buffer capacity. The option d is also correct since it is a consequence of the option f.

Explanation:

The pH of the buffer solution before the addition of HCl is:

[tex]pH = pKa + log(\frac{[KF]}{[HF]})[/tex]

[tex]pH = -log(6.8 \cdot 10^{-4}) + log(\frac{0.371}{0.494}) = 3.04[/tex]  

The hydrochloric acid added will react with the potassium fluoride as follows:

H₃O⁺(aq)  +  F⁻(aq) ⇄   HF(aq) + H₂O(l)

The number of moles (η) of potassium fluoride (KF) and the HF before the addition of HCl is:

[tex] \eta_{KF}_{i} = C_{KF}*V = 0.371 M*1 L = 0.371 mol [/tex]

[tex] \eta_{HF}_{i} = C_{HF}*V = 0.494 M*1 L = 0.494 moles [/tex]

The number of moles of the HCl added is 0.408 moles. Since the number of moles of HCl is bigger thant the number of moles of KF, the moles of HCl that remains after the reaction is:

[tex] \eta_{HCl} = \eta_{HCl} - \eta_{KF}_{i} = 0.408 moles - 0.371 moles = 0.037 moles [/tex]  

Hence, the KF is totally consumed after the reaction with HCl and thus, exceding the buffer capacity.  

We can calculate the pH after the addition of HCl:

HF(aq) + H₂O(l) ⇄ F⁻(aq) + H₃O⁺(aq)    (1)

The number of moles of HF after the reaction of KF with HCl is:

[tex] \eta_{HF} = 0.494 moles + (0.408 moles - 0.371 moles) = 0.531 moles [/tex]

And the concentration of HF after the reaction of KF with HCl is is:

[tex] C_{HF} = \frac{\eta_{HF}}{V} = \frac{0.531 moles}{1 L} = 0.531 moles/L [/tex]

Now, from the equilibrium of equation (1) we have:

[tex] Ka = \frac{[H_{3}O^{+}][F^{-}]}{[HF]} [/tex]

[tex] Ka = \frac{x^{2}}{0.531 - x} [/tex]  (2)

By solving equation (2) for x we have:

x = 0.0187

Finally, the pH after the addition of HCl is:

[tex] pH = -log (H_{3}O^{+}) = -log (0.0187) = 1.73 [/tex]

Therefore, the addition of HCl will exceed the buffer capacity and thus, lower the pH by several units. The correct option is f: an addition of HCl will exceed the buffer capacity. The option d is also correct since it is a consequence of the option f.

I hope it helps you!

Answer:

A) 2.41 * 10^-2 M

Explanation:

Here we go from grams of percipitate to moles of Silver nitrate because we already know NaCl is excess so we don't care about that.

[tex]0.148gAgCl * \frac{1mol AgCl}{143.32 g AgCl} * \frac{1 mol AgNO3}{1 mol AgCl}\\ = 0.00103 mol AgNO3[/tex]

Now that we have moles we know molarity is moles/litres so we just plug it in:

Molarity = mol/litres = 0.00103/0.0428 L = 0.0241 M or 2.41 * 10^-2 M

Answer:

Calcium

Explanation:

Since the element reacts with oxygen to form an oxide with the formula MO, the charge on the element is +2.

Also, since the oxide MO when dissolved in water is basic, the metal is an alkali earth metal.

From the above conditions;

The metal is not arsenic because arsenic is a metalloid has the  following oxides As₂O₃ and As₃O₅ and are respectively amphoteric and acidic in nature

The metal is not germanium because is a metalloid and even though germanium oxide has the formula GeO₂, it is amphoteric.

The metal is not chlorine because chlorine is a non-metal

The metal is definitely calcium because calcium oxide has the formula CaO and calcium is an alkaline earth metal.

The metal is not selenium because selenium is anon-meal and its oxide has the formula Se0₂ and is acidic

Answer:it has fixed quantity

Explanation:energy between chemical bonds is hard to measure

Answer:

It has a fixed quantity.

Explanation:

Answer:

q = - 3.569KJ 0r 3.569KJ Liberated heat (signifying the change in heat is negative)

Explanation:

liberated heat implies that change in heat is negative , therefore

q = -m c ΔT

where, m = mass of the Silver = 249 g

c = specific heat capacity of Silver = 0.235 Jg^{-1} °C^{-1

 ΔT = change in temperature = 87°C- 26 °C= 61°C

q = -m x c x ΔT

= - 249 x 0.235 x 61 = - 3569.415J  rounded to -3569J

Changing to KJ becomes= -3569/1000= - 3.569 KJ

q = - 3.569KJ 0r 3.569KJ liberated heat.

Answer:

D

Explanation:

From given choices it is D.

Answer:

E = 1.47

Explanation:

To do this, you need to apply the Nerst equation which is the following:

E = E° - RT/nF lnQ (1)

Where:

E: cell voltage

E°: Standard potential reduction

R: universal constant

T: temperature of the system

n: number of electrons transfered during the reaction

F: Faraday constant.

Q: Equilibrium constant

However, as the reaction is taking place at 25 °C, and R and F have constant values, we can reduce the above expression to the following:

E = E° - 0.05916/n lnQ  (2)

We can get the value of Q because it has to do with the reaction which is the following:

2IO₃⁻(aq) + 12H⁺(aq) + 5Co(s) ----------> I₂(s) + 5Co²⁺(aq) + 6H₂O(l)

Now, using only the aqueous state the expression of Q will be:

Q = [Co²⁺]⁵ / [H⁺]¹² [IO₃⁻]²

Replacing the values we have:

Q = (7.82)⁵ / (1.54)¹² * (6.64)²

Q = 3.728

Knowing this, all we need to know now is the standard potential reduction of the reaction. To do so, we need to write the two semi equations of reduction and oxidation:

2IO₃⁻ + 12H⁺ + 10e⁻ ---------> I₂ + 6H₂O       E₁° = 1.20 V

5Co ---------> 5Co²⁺ + 10e⁻                          E₂° = 0.28 V

E° = 1.2 + 0.28 = 1.48 V

Now that we have all the values (n = 10) we can write now the nernst equation to calculate the cell voltage:

E = 1.48 - 0.05916/10 ln (3.728)

E = 1.48 - 0.005916 (1.315872)

E = 1.47 V

This will be the cell voltage

Answer: 250 ml of stock solution with molarity of 12.0 M is measured using a pipette and 250 ml of water is added to volumetric flask of 500 ml to make the final volume of 500 ml.

Explanation:

According to the dilution law,

[tex]C_1V_1=C_2V_2[/tex]

where,

[tex]C_1[/tex] = concentration of stock solution = 12.0 M

[tex]V_1[/tex] = volume of stock solution = ?

[tex]C_2[/tex] = concentration of diluted solution= 6.00 M

[tex]V_2[/tex] = volume of diluted acid solution = 500 ml

Putting in the values we get:

[tex]12.0\times V_1=6.00\times 500[/tex]

[tex]V_1=250ml[/tex]

Thus 250 ml of stock solution with molarity of 12.0 M is measured using a pipette and 250 ml of water is added to volumetric flask of 500 ml to make the final volume of 500 ml.

Explanation:

Boiling-point elevation describes the phenomenon that the boiling point of a liquid (a solvent) will be higher when another compound is added, meaning that a solution has a higher boiling point than a pure solvent. This happens whenever a non-volatile solute, such as a salt, is added to a pure solvent, such as water.

Hope it was helpful

Answer:

The correct answer is 28.2 %.

Explanation:

Based on the given question, the partial pressures of the gases present in the trimix blend is 55 atm oxygen, 50 atm helium, and 90 atm nitrogen. Therefore, the sum of the partial pressure of gases present in the blend is,  

Ptotal = PO2 + PN2 + PHe

= 55 + 90 + 50

= 195 atm

The percent volume of each gas in the trimix blend can be determined by using the Amagat's law of additive volume, that is, %Vx = (Px/Ptot) * 100

Here Px is the partial pressure of the gas, Ptot is the total pressure and % is the volume of the gas. Now,  

%VO2 = (55/195) * 100 = 28.2%

%VN2 = (90/195) * 100 = 46%

%VHe = (50/195) * 100 = 25.64%

Hence, the percent oxygen by volume present in the blend is 28.2 %.  

Answer:

This is because Hydrogen peroxide must be acidic, thereby making hydrogen ions taking part in the reaction which act as reactant. It is important also to use H2SO4 because permanganate is a strong oxidizing agent and it cannot oxidize sulphuric acid if enough is added but it can oxidize chloride ions to chlorine if hydrochloric acid is used.

Explanation:

Hydrogen peroxide is used as a chemical agents in cleaning processes for chemical industries and semiconductor plants. In the hydrogen peroxide assay, sulphuric acid is used and the reaction is an exothermic reaction. This produce strong peroxysulphuric acid

Answer:

0.0586 kg

Explanation:

From the question,

Heat lost by the aluminium = heat gain by nitrogen.

CM(t₁-t₂) = cm................... Equation 1

Where C = Specific heat capacity of aluminum, M = mass of aluminum, t₂ = Final temperature, t₁ = initial temperature, c = latent heat of vaporization of nitrogen, m = mass of nitrogen.

make m the subject of the equation

m = CM(t₁-t₂)/c................ Equation 2

Given: C = 900 J/kg.K, M = 60 g = 0.06 kg, t₁ = 20 °C, t₂ = -196 °C

Constant: c = 199200 J/kg

Substitute these values into equation 2

m = 900×0.06×[20-(-196)]/199200

m = 900×0.06×216/199200

m = 0.0586 kg.

Answer:

[tex]m_{N_2}=58.6gN_2[/tex]

Explanation:

Hello,

In this case, for an average temperature of -176 °C, the vaporization enthalpy of liquid nitrogen is 199.2 J/g, thus, we first compute the heat lost by the aluminium by considering it cooled mass, specific heat and temperature change:

[tex]Q=mCp(T_2-T_1)=60g*0.90\frac{J}{g\°C}*(-196-20)\°C\\ \\Q=-11664J[/tex]

Next, heat lost by the aluminium is gained by the nitrogen:

[tex]-Q_{Al}=Q_{N_2}=11664J[/tex]

Therefore, the vaporized nitrogen is:

[tex]m_{N_2}=\frac{Q_{N_2}}{\Delta H_v}=\frac{11664J}{199.2J/g}\\\\m_{N_2}=58.6gN_2[/tex]

Best regards.