A chemist needs to make an acidic solution that is 0.25 M in acetic acid (HC 2 H 3 O 2 ). If she plans to prepare 250mL of solution, how much acetic acid must she use to prepare the solution.

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:

Explanation:

According to research :

Methanol is a polar molecule:

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

Answer:

B) THE DEPTH OF THE LAKE IS 0.060 m

Explanation:

b) Determine the depth of the lake in metres

1. Using the general gas law, we will calculate the initial pressure of the air bubbles.

P1V1 /T1 = P2V2/T2

P1 = Unknown

T1 = 5.24 °C

T2 = 18.73 °C

P2 = 0.973 atm

V1 = V1

V2 = 6V1

P1 = P2 V2 T1 / V1 T2

P1 = 0.973 * 6V1 * 5.24 / V1 * 18.73

P1 = 5.09852 * 6 / 18.73

P1 = 30.59112 / 18.73

P1 = 1.633 atm.

2. Calculate the depth of the lake:

             Pressure = length * density * acceleration

            length = Pressure / density * acceleration

Pressure = 1.633 atm = 1.633 * 101, 325 Nm^2 = 165, 463.725 Nm^2

Density =  1.02 g/cm3 = 1.02 * 10^3 kg/m^3

Acceleration = 9.8 m/s^2

So therefore, the length in metres is:

Length = density * acceleration / pressure

Length =  1.02 *10^3 * 9.8 / 165, 463.725  

Length = 9.996 * 10^3 / 165 463.725

Length = 0.06 m

Hence, the depth of the lake is 0.06 m

Answer:

18.7887 g of NaCl

Explanation:

The question reads - How many grams of NaCl will be produced from 18.0 g of Na and 23.0 g of Cl2?

Let us start by writing out the balanced equation of the reaction:

Na + Cl2 ---> NaCl2

1 mole, each of Na and Cl2 is required to produce 1 mole of NaCl.

mole = mass/molar mass

Therefore

18 g of Na = 18/23 = 0.7826 mole

23 g of Cl2 = 23/71 = 0.3239 mole

In this case, the Na is in excess and the Cl2 becomes the limiting reagent. Hence

0.3239 mole of Cl2 will react with 0.3239 mole of Na to yield 0.3239 mole of NaCl.

mass of 0.3239 mole NaCl = 0.3239 x 58 = 18.7887 g

Hence, 18.7887  grams of NaCl will be produced from 18.0 g of Na and 23.0 g of Cl2.

Answer: Yes

Explanation: Since strong acids react with and use up water molecules, and strong bases do not

Answer:

C6H6 < C7H15OH < C6H13OH < C2H5OH

Explanation:

Hello,

In this case, since the organic molecules solubility is defined in terms of the presence of hydrogen bonds as intermolecular forces, which are formed between oxygen and hydrogen and the length of the organic chain, we can notice that hydroxyl-containing longer chains tend to be less water soluble whereas shorter chains more soluble as the polar part of the chain will lead the solubility. In addition to it, chains with lack of oxygen tend to be highly water insoluble. Therefore, we can notice that C6H6 is the least water soluble, next C7H15OH, then C6H13OH and the most soluble is C2H5OH.

Best regards.

Answer:

substituting unsaturated fats—like those found in olive oil—for saturated fats could lower your chance of developing heart disease. 

Answer:

1.00 M

Explanation:

Step 1: Write the balanced equation

HBr + LiOH ⇒ LiBr + H₂O

Step 2: Calculate the reacting moles of lithium hydroxide

40.00 mL of 0.500 M solution react. The reacting moles of LiOH are:

[tex]40.00 \times 10^{-3} L \times \frac{0.500mol}{L} = 0.0200 mol[/tex]

Step 3: Calculate the reacting moles of hydrobromic acid

The molar ratio of HBr to LiOH is 1:1. The reacting moles of hydrobromic acid are 1/1 × 0.0200 mol = 0.0200 mol.

Step 4: Calculate the molarity of hydrobromic acid

0.0200 moles of HBr are in 20.00 mL of the solution. The molarity of the hydrobromic acid solution is:

[tex]M= \frac{0.0200 mol}{20.00 \times 10^{-3} L } =1.00 M[/tex]

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:

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.\

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: D=8.27 g/cm³

Explanation:

Density is mass/volume. Mass is in grams and volume is in liters. In this case, the problem wants our volume to be in cm³. All we need to do is to make some conversions to convert kg/m³ to g/cm³.

[tex]D=\frac{38.3kg}{0.00463m^3} *\frac{(1m)^3}{(100cm)^3} *\frac{1000g}{1kg}[/tex]

With this equation, the m³ and kg cancel out, and we are left with g/cm³.

D=8.27 g/cm³

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.  

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:

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: 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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Answer:

  6.0221409e+23

Explanation:

The number of molecules in a mole of any substance is Avogadro's number, 6.0221409e+23.

Explanation:

It is given that,

Dimension of a solid block of substance is 74.0 cm by 55.0 cm by 29.0 cm

Mass of solid block is 625 kg or 625000 grams

We need to find the density of solution. The mass per unit its volume is called density.

[tex]\rho=\dfrac{m}{V}\\\\\rho=\dfrac{625000}{74\times 5\times 29}\\\\\rho=58.24\ g/cm^3[/tex]

So, the density of solid block is [tex]58.24\ g/cm^3[/tex]. The density of water is [tex]1\ g/cm^3[/tex]. The density of block is more than water. Hence, it will sink.

A student should start with 4.74 mL of the 12.0 M HCl to prepare 65.0 mL of 0.875 M HCl from 12.0 M HCl.

Molarity (M) is the amount of a substance in a certain volume of solution.

Molarity is defined as the moles of a solute per liters of a solution.

Molarity is also known as the molar concentration of a solution.

Formula used for the given question ;

M₁V₁ = M₂V₂

M₁V₁ = M₂V₂

   V₁      =  0.875M x 65.0 mL / 12.0 M HCl.

            =  4.74 ml

Therefore , A student should start with 4.74 mL of the 12.0 M HCl to prepare 65.0 mL of 0.875 M HCl from 12.0 M HCl.

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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:

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: 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: From experience and observation, the pathogen that responds more faster to treatments are PARASITES.

This is because, our body are already used to parasite, as they feed and mostly live inside our body. Parasites becomes harmful to our body, when it is allowed to be much in the body, thereby weakening the immune system of the body. Intake of vaccination reduces the number of parasites in the body, which gives the immune system the chance of recovering and protecting the body.

Parasite does not replicate more faster like viruses and other pathogens. These makes it more easier for treatment to work more faster. They are also easily killed by taking the proper treatment, and the rate of their replications are very slow when compared to the rate of their death when vaccinated.

Some example disease caused by parasites are:

1) Giardiasis

2) Trichomoniasis

3) Malaria

4) Toxoplasmosis

5) Intestinal worms

6) Pubic lice

All this disease above responds very fast to medical treatment, unless when they is complications, which are mostly when the parasite has been allowed to cause more harm and replicate much in the body, without any treatment. This is why doctors advice patients that lives at the tropical regions to periodically vaccinate themselves on parasitic infections.

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:

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 =

Answer:

Solids have a definite shape and volume. Liquids have a definite volume, but take the shape of the container. Gases have no definite shape or volume.

Explanation:

Answer:

Liquids properties include retention of volume and its conformation to the shape of its container. The  

particles in a liquid have more kinetic energy than the particles in the corresponding solid. Solids are  

structurally rigid and resist changing shape or volume. Solid particles have the least amount of kinetic  

energy. Properties of gas include easily compressible, the expand to fill their container and they occupy  

more space than a solid or liquid. Gas particles have the most amount of kinetic energy

Explanation:

Answer:

The correct option is B

b. Phosphorylation by a kinase using ATP (which turns the complex off) and dephosphorylation by a phosphatase (which turns the complex on).

Explanation:

The pyruvate dehydrogenase complex is described as a complex having many enzymes that catalyse decarboxylation of pyruvate by oxidation to yield NADH and acetyl‐CoA, which makes the influx of acetyl-coA from glycolysis to increase into the Krebs cycle.

It can be found in the mitochondrial matrix and pyruvate which is conveyed through enzyme Pyruvate Translocase to PDH complex.

Regulation of pyruvate dehydrogenase complex occured through allosteric effectors as well as phosphorylation.the main regulatory processes controlling pyruvate dehydrogenase's activity in eukaryotes such as plants and animals Phosphorylation is by a kinase using ATP which first turns the complex off and the later dephosphorylation by a phosphatase which turns the complex on

Answer:

THE AMOUNT OF THE SAMPLE REMAINING AFTER 5 HOURS IS 1250 CPM

Explanation:

A sample has a half life of 100 minutes. To solve for the amount remaining after a given amount of 10000CPM decay in 5 hours, we use the formula:

Nt = No * (1/2)^t/t1/2

Where:

Nt = amount remaining = unknown

No = initial amount = 10000 CPM

t = time elapsed for decay = 5 hours = 60*5minutes = 300 minutes

t1/2 = half life = 100 minutes

Putting the values into the formula, we have:

Nt = 10000 * (1/2)^ 300/100

Nt = 10000 * (1/2)^3

Nt = 10000 * 0.125

Nt = 1250 CPM

The amount of the sample remaining after 5 hours is 1250 CPM.