A student wishes to prepare 65.0 mL of 0.875 M HCl from 12.0 M HCl.

What volume of the
12.0 M HCl should he/she start with?

Answer: 32 mol HCI

Explanation:

Molarity of a solution is defined as the number of moles of solute dissolved per liter of the solution.

[tex]Molarity=\frac{n}{V_s}[/tex]

where,

n = moles of solute

[tex]V_s[/tex] = volume of solution in Liters

Now put all the given values in the formula of molarity, we get

[tex]4.0M=\frac{moles}{8.0L}[/tex]

[tex]moles={4.0M\times 8.0L}=32mol[/tex]

Therefore, the moles of HCI needed to prepare 8.0 liters of a 4.0 M solution of HCI are 32.

Answer:

The standard enthalpy of formation of NOCl(g) at 25 ºC is 105 kJ/mol

Explanation:

The ∆H (heat of reaction) of the combustion reaction is the heat that accompanies the entire reaction. For its calculation you must make the total sum of all the heats of the products and of the reagents affected by their stoichiometric coefficient (number of molecules of each compound that participates in the reaction) and finally subtract them:

Enthalpy of the reaction= ΔH = ∑Hproducts - ∑Hreactants

In this case, you have:  2 NOCl(g) → 2 NO(g) + Cl₂(g)

So, ΔH=[tex]2*H_{NO} +H_{Cl_{2} }-2*H_{NOCl}[/tex]

Knowing:

Replacing:

75.5 kJ/mol=2* 90.25 kJ/mol + 0 - [tex]H_{NOCl}[/tex]

Solving

-[tex]H_{NOCl}[/tex]=75.5 kJ/mol - 2*90.25 kJ/mol

-[tex]H_{NOCl}[/tex]=-105 kJ/mol

[tex]H_{NOCl}[/tex]=105 kJ/mol

The standard enthalpy of formation of NOCl(g) at 25 ºC is 105 kJ/mol

Answer:

101

Explanation:

Provided that

[tex]S_1 = S_2 = same\ V_{max}[/tex]

And,

[tex]S_1\ k_M = 2.0mM\\S_2\ k_M = 20mM[/tex]

Now we expect the same

{S} (0.1mM)

This determines that [tex]S_1[/tex] generates a  higher rate of product formation as compared to the [tex]S_2[/tex]

So we can easily calculate the [tex]V_{max}[/tex] for either of [tex]S_1[/tex] or [tex]S_2[/tex] as we know that Tube 1 is [tex]S_2[/tex] and tube 2 is [tex]S_1[/tex]

As we know that

[tex]V_0 = V_{max}\ {S} / (K_M + {S})[/tex]

As the rates do not include any kind of units so we do not consider the units for [tex]V_{max}[/tex]

Now the calculation is

[tex]0.5 = V_{max} (0.1\ mM) / (20\ mM + 0.1\ mM)[/tex]

[tex]V_{max} = 0.5 (20.1\ mM) / 0.1\ mM[/tex]

= 100.5

≈ 101

Answer:

Explanation:

According to research :

Methanol is a polar molecule:

The alcohol (-OH) group dominates the molecule making it definitely polar.

Answer:

Grams of mercury= 0.06 g of Hg

Note: The question is incomplete. The complete question is as follows:

A compact fluorescent light bulb contains 4 mg of mercury. How many grams of mercury would be contained in 15 compact fluorescent light bulbs?

Explanation:

Since one fluorescent light bulb contains 4 mg of mercury,

15 such bulbs will contain 15 * 4 mg of mercury = 60 mg

1 mg = 0.001 g

Therefore, 60 mg = 0.001 g * 60 = 0.06 g of mercury.

Compact fluorescent lightbulbs (CFLs) are tubes containing mercury and noble gases. When electricity is passed through the bulb, electron-streams flow from a tungsten-coated coil. They collide with mercury atoms, exciting their electrons and creating flashes of ultraviolet light. A phosphor coating on the inside of the tube absorbs this UV light flashes and re-emits it as visible light. The amount of mercury in a fluorescent lamp varies from 3 to 46 mg, depending on lamp size and age.

Total amount of mercury in 15 compact fluorescent light bulbs is 0.06 gram of mercury.

What information do we have?

Number of compact fluorescent light bulbs = 15 bulb

Amount of mercury in each bulb = 4 mg

Total amount of mercury = Number of compact fluorescent light bulbs × Amount of mercury in each bulb

Total amount of mercury = 15 × 4

Total amount of mercury = 60 mg

Total amount of mercury = 60 / 1000

Total amount of mercury = 0.06 gram of mercury

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Answer: I think so.. (sorry if i am wrong)

Explanation:  Familiar examples of physical properties include density, color, hardness, melting and boiling points, and electrical conductivity. A physical property is a characteristic of matter that is not associated with a change in its chemical composition.

Answer: Pollutant

Explanation:

Answer:

Explanation:

The substance that could be found in air, water or soil that is harmful to humans or animals is called pollutant.

Answer: a. new

Explanation:

The time between one full moon to another is new moon. The lunation is the average time taken for the formation of new moon to the next. The new moon is the initial visible crescent of the Moon after being conjugated with the Sun. Per lunar cycle can be assigned with a lunation number for the purpose of identification.

Answer:

The molality of this solution is 0.368 molal

Explanation:

Step 1: Data given

Mass of CaCl2 = 10.2 grams

Molar mass of CaCl2 = 110.98 g/mol

Mass of water = 250 grams = 0.250 kg

Step 2: Calculate the number of moles CaCl2

Moles CaCl2 = mass CaCl2 / molar mass CaCl2

Moles CaCl2 = 10.2 grams / 110.98 g/mol

Moles CaCl2 = 0.0919 moles

Step 3: Calculate the molality of the solution

Molality solution = moles CaCl2 / mass water

Molality solution = 0.0919 moles / 0.250 kg

Molality solution = 0.368 mol / kg = 0.368 molal

The molality of this solution is 0.368 molal

Answer:

0.367 m

Explanation:

We have to start with the molality equation:

[tex]m=\frac{mol~of~solute}{Kg~of~solvent}[/tex]

If we want to calculate the molality we need the moles of the solute and the Kg of the solvent. In this case the solute is [tex]CaCl_2[/tex] and the solvent is [tex]H_2O[/tex].

Lets start with the the moles of solute. For this calculation we need the molar mass of [tex]CaCl_2[/tex] ([tex]111~g~CaCl_2[/tex]) and the mass, so:

[tex]10.2~g~CaCl_2\frac{1~mol~CaCl_2}{111~g~CaCl_2}[/tex]

[tex]0.0918~mol~CaCl_2[/tex]

Now, we can calculate the Kg of solvent, if we do the conversion from grams to Kg:

[tex]250~g~CaCl_2\frac{1~Kg}{1000~g}[/tex]

[tex]0.25~Kg[/tex]

With these values we can calculate the "molality":

[tex]m=\frac{0.0918~mol~CaCl_2}{0.25~Kg}[/tex]

[tex]m=0.3672[/tex]

I hope it helps!

The given question is incomplete, the complete question is:

Suppose 1.27 g of potassium iodide is dissolved in 100. mL of a 44.0 m M aqueous solution of silver nitrate. Calculate the final molarity of iodide anion in the solution. You can assume the volume of the solution doesn't change when the potassium iodide is dissolved in it. Round your answer to 3 significant digits.

Answer:

The correct answer is 0.0325 M.

Explanation:

The mass of potassium iodide or KI mentioned in the question is 1.27 grams, the molar mass of KI is 166 g/mol. The formula for determining the no of moles of the substance is mass/molar mass. Thus, the moles of KI in 1.27 grams will be,  

= 1.27g / 166 g/mol = 0.00765 moles.  

KI = K⁺ + I⁻

Therefore, the moles of KI will be equivalent to moles of iodide anion, that is, 0.00765 moles.  

The moles of silver nitrate or AgNo3 in the solution can be determined by using the formula, molarity (M) * volume in liters. The molarity of silver nitrate given in the question is 44 mM and the volume used is 100 ml or 100/1000 L. Now putting the values we get,  

= (44 M/1000) * (100 L/1000) = 0.0044 moles

The moles of silver nitrate is equivalent to moles of silver ion, which is further equivalent to the moles of iodide ion that has taken part in precipitation = 0.0044 moles.  

The moles left of I⁻ in the solution will be,  

0.00765 - 0.0044 = 0.00325

Now, the final molarity of iodide ion in the solution will be,  

= moles/volume in liters

= 0.00325 moles / 0.100 L = 0.0325 M

Answer: Wind current

Explanation:

The wind current is the main driving force along with the water currents when one reaches to the seashore. The wind currents above surface of water generates due to the evaporation of water.

The strong wind currents can pull any animal or human walking or running near the sea shore. These currents bring the animal or human towards the sea.

Answer:

pH = 7.1581

Explanation:

The equilibrium of NaHSO₃ with Na₂SO₃ is:

HSO₃⁻ ⇄ SO₃²⁻ + H⁺

Where K of equilibrium is the Ka2: 6.5x10⁻⁸

HSO₃⁺ reacts with NaOH, thus:

HSO₃⁻ + NaOH → SO₃²⁻ + H₂O + Na⁺

As the buffer is of 1.0L, initial moles of HSO₃⁻ and SO₃²⁻ are:

HSO₃⁻: 0.252 moles

SO₃²⁻: 0.139 moles

Based on the reaction of NaOH, moles added of NaOH are subtracting moles of HSO₃⁻ and producing SO₃²⁻. The moles added are:

0.0500L ₓ (1mol /L): 0.050 moles of NaOH.

Thus, final moles of both compounds are:

HSO₃⁻: 0.252 moles - 0.050 moles = 0.202 moles

SO₃²⁻: 0.139 moles + 0.050 moles = 0.189 moles

Using H-H equation for the HSO₃⁻ // SO₃²⁻ buffer:

pH = pka + log [SO₃²⁻] / [HSO₃⁻]

Where pKa is - log Ka = 7.187

Replacing:

pH = 7.187 + log [0.189] / [0.202]

Answer:

mass of ethanolamine 61.2 g

Explanation:

Data:

V (Volume) = 60 mL

ρ (Density)= 1.02 [tex]\frac{g}{cm^{3} }[/tex] = 1.02 [tex]\frac{g}{mL}[/tex]

With the given data and using the density formula:

ρ = [tex]\frac{mass}{volume}[/tex]

It is possible to calculate the grams of ethanolamine that the student should weigh out. The mass in the formula is cleared and the data is replaced.

mass =  ρ * volume

mass = 1.02 [tex]\frac{g}{mL}[/tex] * 60 mL = 61.2 g of ethanolamine

Answer:

molar mass of the phosphorus chloride = 138.06 g/mol

Explanation:

mass of phosphorus will be the same as mass of CO2, since it is stated that they are of equal amount.

mass = 3.51 g

lets assume that it took the CO2 1 sec to effuse, then the time taken by the phosphorus chloride will be 1.77 sec

From this we can say that

rate of effusion of CO2 = 3.51/1 = 3.51 g/s

rate of effusion of the phosphorus chloride = 3.51/1.77 = 1.98 g/s

From graham's equation of effusion,

[tex]\frac{Rc}{Rp}[/tex] = [tex]\sqrt{\frac{Mp\\}{Mc} }[/tex]

Rc = rate of effusion of CO2 = 3.51 g/s

Rp = rate of effusion of phosphorus chloride = 1.98 g/s

Mc = molar mass of CO2 = 44.01 g/mol

Mp = molar mass of the phosphorus chloride = ?

Imputing values into the equation, we have

[tex]\frac{3.51}{1.98}[/tex] = [tex]\sqrt{\frac{Mp\\}{44.01} }[/tex]

1.77 = [tex]\frac{\sqrt{Mp} }{6.64}[/tex]

11.75 = [tex]\sqrt{Mp}[/tex]

Mp = [tex]11.75^{2}[/tex]

Mp = molar mass of the phosphorus chloride = 138.06 g/mol

Answer

Molarity = [tex]1.4mol/L[/tex]

Explanation:

Molarity provides the number of moles of solute per liter of solution (moles/Liter). It is a means by which concentration of solution is measured.

SEE THE ATTACHMENT BELOW FOR STEP BY STEP SOLUTION.

Answer:

1.42 M

Explanation:

In this case have a dilution problem, therefore we need to use the dilution equation:

[tex]C_1*V_1=C_2*V_2[/tex]

What values we have?

[tex]C_1=3.82M[/tex]

[tex]V_1=526mL(0.516L)[/tex]

[tex]C_2=?[/tex]

[tex]V_2=?[/tex]

Now, we can calculate [tex]V_2[/tex] if we add the volumes, so:

[tex]0.516~L+~0.875~L=1.391~L[/tex]

So,  [tex]V_2=1.391~L[/tex]

We can plug the values in the equation:

[tex]3.82~M*0.516~L=C_2*1.391~L[/tex]

[tex]C_2=\frac{3.82~M*0.516~L}{1.391~L}[/tex]

[tex]C_2=1.42~M[/tex]

I hope it helps!

Answer:

3.1°C

Explanation:

Using freezing point depression expression:

ΔT = Kf×m×i

Where ΔT is change in freezing point, Kf is freezing point depression constant (5.12°c×m⁻¹), m is molality of the solution and i is Van't Hoff factor constant (1 For I₂ because doesn't dissociate in benzene).

Molality of 9.04g I₂ (Molar mass: 253.8g/mol) in 75.5g of benzene (0.0755kg) is:

9.04g ₓ (1mol / 253.8g) = 0.0356mol I₂ / 0.0755kg = 0.472m

Replacing in freezing point depression formula:

ΔT = 5.12°cm⁻¹×0.472m×1

ΔT = 2.4°C

As freezing point of benzene is 5.5°C, the new freezing point of the solution is:

5.5°C - 2.4°C =

From the data provided;

A buffer is a solution which resists changes to its pH when a small quantity of acid or base is added to it.

The buffer capacity is determined using the Henderson-Hasselbach equation:

For Buffer A: pH = 4.74 + log(0.10/010) = 4.74

Buffer B: pH = 4.74 + log(0.30/030) = 4.74

For Buffer C: pH = 4.74 + log (0.10/0.50) = 4.04

Buffer A and Buffer B has same pH value as the pKa of acetic acid.

However, Buffer B has higher concentration of the components compared to buffer A, therefore, Buffer B has the highest buffer capacity.

The pH of buffer C is lower than pKa of acetic acid. Hence, buffer C has the lowest buffer capacity.

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Answer:

63.33%

Explanation:

To find the percentage of sugar in the milk chocolate just divide 15 by 9.5. This will give you 0.63333 (recurring). To find the percentage, times it by 100, which will give you 63.33%.

Hope this helped :)

The percentage of sugar present in the milk would be  63.33 %.

In positional notation, significant figures refer to the digits in a number that is trustworthy and required to denote the amount of something, also known as the significant digits, precision, or resolution.

As given in the problem a 15.00 g milk chocolate bar contains 9.500 grams of sugar, and we have calculated the percentage of sugar present,

The percentage of sugar present in the milk = 9.500 ×100/15

                                                                                = 63.33 %

Thus, the percentage of sugar present in the milk would be 63.33 %.

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Answer: 8.0 moles

Explanation:

0.6661 moles×12 H≈8.0 moles

120 g of C₆H₁₂O₆ contain 8 moles of Hydrogen atoms

To obtain the answer to the question given above, we'll begin by calculating the mass of 1 mole of C₆H₁₂O₆

1 mole of C₆H₁₂O₆ = (12×6) + (12×1) + (16×6)

= 72 + 12 + 96

From the above,

We can see that 180 g of C₆H₁₂O₆ contains 12 moles of Hydrogen.

Finally, we shall determine the number of mole of Hydrogen atoms in 120 g of C₆H₁₂O₆. This can be obtained as follow:

180 g of C₆H₁₂O₆ contains 12 moles of Hydrogen.

Therefore,

120 g of C₆H₁₂O₆ will contain = [tex]\frac{120 * 12}{180}[/tex] = 8 moles of Hydrogen.

Thus, 120 g of C₆H₁₂O₆ contain 8 moles of Hydrogen atoms

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Explanation:

First off, we have to understand what we means by oxidation and reduction.

Oxidation is the loss of electrons during a reaction by a molecule, atom or ion. Oxidation occurs when the oxidation state of a molecule, atom or ion is increased.

Reduction on the other hand is the opposite of oxidation. It is the gain of electrons during a reaction by a molecule, atom or ion. Reduction occurs when the oxidation state of a molecule, atom or ion decreases.

Back to the question;

oxidation is what happens when a reactant loses electrons.

Reduction occurs when a reactant gains electrons in the reaction.

Answer: A

Explanation: Heat is the temperature of an object.

Answer:

Option C

the energy transferred between objects at different temperature.

Answer:Fractional distillation of air. About 78 per cent of the air is nitrogen and 21 per cent is oxygen. These two gases can be separated by fractional distillation of liquid air.

Explanation:

Answer:

578mL is the volume you need to dissolve the mass of KBr

Explanation:

The percent by mass volume, % (w/v) is defined as the ratio between mass of solute in grams and volume of the solution in mililiters times 100. The formula is:

% (w/v) = mass solute (g) / volume solution (mL) × 100

As you want a solution 8.48% and the solute is 49.0g of KBr:

8.48% = 49.0 (g) / volume solution (mL) × 100

Volume solution = 578mL is the volume you need to dissolve the mass of KBr

Answer:

d) The fraction of collision with total kinetic energy larger than activation energy  increases.

Explanation:

Hello,

In this case, kinetic models explain how the rate of a chemical reaction is affected by several factors. In such a way, specifically for temperature, when it increases, the average velocity of the particles is also increased, for that reason, the collision frequency increases since the molecules are more likely to collide as they move faster and encounter to each other.

Nonetheless, it is the minor reason because the main reason is that the effective collisions increase when the temperature is increased, and they are related with the fraction of collision with total kinetic energy that turns out larger than the activation energy, therefore, answer is d).

Best regards.

Answer:

What happens to the wavelength when you increase the rate of vibration (how fast your hand moved back and forth). After increasing the rate of vibration, the wavelength decreased.\

Examples A and B are examples of chemical reaction as new substances are formed in these reactions  which have different chemical compositions.

Chemical reactions are defined as reactions which occur when a substance combines with another substance to form a new substance.Alternatively, when a substance breaks down or decomposes to give new substances it is also considered to be a chemical reaction.

There are several characteristics of chemical reactions like change in color, change in state , change in odor and change in composition . During chemical reaction there is also formation of precipitate an insoluble mass of substance or even evolution of gases.

There are three types of chemical reactions:

1) inorganic reactions

2)organic reactions

3) biochemical reactions

During chemical reactions atoms are rearranged and changes are accompanied by an energy change as new substances are formed.

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Answer:

iron (Fe)

Explanation:

Use q = mcΔT.

q = 1.396 x 10^2 J

m = 15.5g

ΔT = (45.0 - 25.0) = 20 degrees celcius

1.396 x 10^2 = 15.5 x c x 20

c = .450 J/g x degrees celcius

This is closest to the specific heat of iron/steel.

Answer:

3.01×10²³ particles.

Explanation:

From Avogadro's hypothesis, we understood that 1 mole of any substance contains 6.02×10²³ particles. This implies that 1 mole of N2O5 also contains 6.02×10²³ particles.

Now, if 1 mole of N2O5 contains 6.02×10²³ particles ,

Then 0.5 mole of N2O5 will contain = 0.5 × 6.02×10²³ = 3.01×10²³ particles.

Therefore, 0.5 mole of N2O5 contains 3.01×10²³ particles.

Answer:

c. I, II and III

Explanation:

The cell is as follows

Cr / Cr⁺²(1M) // H⁺ ( 1 M ) / H₂

Standard reduction potential of hydrogen cell is zero . Standard reduction potential is negative E for Cr⁺² / Cr(1M) half cell

Cell potential = Ecathode - Eanode

= 0 - ( - E)

= E

E is cell potential and also standard cell potential or emf of the cell .

Standard reduction potential that is for Cr3+/Cr.  is  - E .

Hence statement I , II , III are right . IV th statement is wrong because of sign

Option c is correct.

The branch of chemistry which deals with electricity is called electrochemistry.

The correct answer is C

The cell representation is as follows:-

The standard reduction potential of hydrogen cells is zero. Standard reduction potential is negative E for Cr⁺² / Cr(1M) half cell because it will behave as a cathode.

The formula of the electric cell is as follows :-[tex]Cell potential = E_{cathode} - E_{anode[/tex]

After putting the value the cell potential will be:-

Cell potential = 0 - ( - E)

The standard reduction potential that is for [tex]Cr^{3+}/Cr = - E .[/tex]

Hence, the correct option is C that is I, II, and IV.

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Answer:

Explanation:

Lowering of vapour pressure of solvent is proportional to number of moles   of solute dissolved in it per litre .

No of moles of glucose dissolved

= mass dissolved / molecular weight of glucose

= 10 / 180

= .055  moles.

No of moles of sucrose dissolved = 10 / 342

= .029 moles.

So reduction in vapour pressure will be lower of  solution dissolving sucrose . It is so because , no of moles of solute dissolved in it is low.