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Which buffer can be suitable to prepare a solution that needs to be buffered at pH 4? Explain your

choice.

A. Formic acid/Formiate buffer

B. Carbonic acid/Bicarbonate buffer

C. Ammonia/Ammonium buffer

D. Any buffer will work.

E. None of the buffers will be suitable.

34 Which of the following will form a buffer when mixed together? Explain a weak acid/base and its conjugate base/acid in the form of salt

Answer:

3.76375e+22

Explanation:

(2/32)×(6.022 × 10^23)

Answer

Q = mcΔT

Qwater = -Qmetal

(100 g)(4.18 J/g°C)(25°C - 20°C) = -(50 g)c(25°C - 90.0°C)

2090 J = (3250 g °C)c

c = 0.643 J/g °C

Rice would not show any negative test with Benedicts solution but will show  blue black color with iodine.

The Benedicts solution is used to test for the presence of reducing sugars in a solution. The brick red color is a positive test for reducing sugars such as glucose.

Owing to the fact that grape does not have starch, it shows a negative test for starch. Rice would not show any negative test with Benedicts solution but will show  blue black color with iodine.

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Answer:

Combination reaction

This reaction is a combination reaction because calcium oxide and water combine to create calcium hydroxide as the only result.

An inorganic substance called calcium hydroxide has several uses. It is also known as slaked lime, and limewater is the name of its aqueous solution.

Calcium hydroxide has the chemical formula Ca in both its composition and structure (OH)

2

and it has a 74.09 g/mol molar mass.

The calcium metal cation is linked to two hydroxide anions in this ionic molecule. Calcium hydroxide has a polymeric structure in its solid state, which is made possible by hydrogen bonds between the layers.

The mineral portlandite, a naturally occurring but seldom type of calcium hydroxide, is present in various volcanic and metamorphic rocks.

In order to make calcium hydroxide for use in industry, calcium oxide (lime or quicklime) is reacted with water.

CaO + H

2

O → Ca(OH)

2

On lesser scales, it may also be produced through the reaction of aqueous calcium chloride and sodium hydroxide.

Physical characteristics: It has a melting point of 580 °C and can be found as white powder or colorless crystals with a density of 2.21 g/cm3.

Chemical characteristics: Water may rather easily dissolve calcium hydroxide. It partly dissolves in water to create limewater, a moderately basic solution. Ca(OH)2 solution or limewater

salts when combined with acids, and it can corrode various metals, including aluminum. The process of carbonatation, which produces calcium carbonate from limewater and carbon dioxide, is advantageous:

Ca(OH)2+ CO2→ CaCO3+ H2O

Uses: Calcium hydroxide is used in a wide range of industrial processes, including the production of Kraft paper, water and sewage treatment, the production of ammonia, and pH adjustment. Additionally, it is a crucial component of mortars, cement, and plaster. It may be used in the food business for a variety of purposes, including pH correction, calcium fortification, digestion help, and baking soda replacement because it is a relatively non-toxic and gentle base.

Calcium hydroxide is not poisonous at low doses and poses no safety risks. However, inhaling, eating, or coming into touch with the aqueous calcium hydroxide solution at greater concentrations might result in lung damage, chemical burns, blindness, or serious skin irritation.

Answer:

5.06 M LiCl

Explanation:

To find the new molarity of the solution, you need to (1) find the amount of moles LiCl (via the molarity equation using the original molarity and volume) and then (2) calculate the new molarity (via the molarity equation using the new volume and old moles). The final answer should have 3 sig figs to match the given values.

Molarity (M) = moles / volume (L)

Step (1)

381 mL / 1,000 = 0.381 L

Molarity = moles / volume

9.96 M = moles / 0.381 L

(9.96 M) x (0.381 L) = moles

3.79 = moles

Step (2)

750 mL / 1,000 = 0.750 L

Molarity = moles / volume

Molarity = 3.79 moles / 0.750 L

Molarity = 5.06 M

If two objects at different temperatures are brought in contact with each other, energy is transferred from the hotter object to the colder object.

The total energy of an isolated system remains constant irrespective of whatever internal changes may take place with energy conevrting in one form and reappearing in another.

When two substances at different temperatures come into contact, the substance with a higher temperature will transfer heat energy to the substance with a lower temperature, until their temperatures get equal.

Here, if the two substances are isolated then the law of conservation of energy states that the when heat released by the substance with a higher temperature is the same amount of heat gained by the substance lower a lower temperature.

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Sucrose doesn't show appreciable dissociation in water, so i≈1 in this case. by extension, −7.3°C is the approximate freezing point of this solution.

The temperature at which a liquid solidifies.

Sucrose doesn't show appreciable dissociation in water, so i≈1 in this case. by extension, −7.3°C is the approximate freezing point of this solution.

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Avogadro's law states that in each mole of a substance, there are [tex]6.022 \times 10^{23}[/tex] particles.

This means that 15000 atoms is equal to [tex]\frac{15000}{6.022 \times 10^{23}}=\boxed{2.4909 \times 10^{-20} \text{ moles (to 5 sf)}}[/tex]

There are 2.49 × [tex]10^{-20}[/tex] moles present in 15000 atoms of iron (Fe).

A mole is the quantity of a material that includes 6.023 x [tex]10^{23}[/tex] of that substance's components.

The smallest component of ordinary stuff that makes up a chemical element would be an atom.

Calculation of mole

It is known that 1 mole =  6.023 x [tex]10^{23}[/tex] particles.

So, the 1500 atoms will be equal to the = 1500 /  6.023 x [tex]10^{23}[/tex]  =  2.49 × [tex]10^{-20}[/tex] moles .

Therefore, there are 2.49 × [tex]10^{-20}[/tex] moles present in 15000 atoms of iron (Fe).

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Answer:

B.) As a medium star

Explanation:

A.) is incorrect. It is not a giant star because there a millions are stars which are much more massive.

B.) is correct. Our Sun has a radius of about 437,000 miles. Technically our Sun is classified as a G-type main-sequence star, aka. yellow dwarf star. The Sun is generally classified as this type of star.

C.) is incorrect. While the Sun's light is similar to the light of white dwarf, it is still most certainly classified as a yellow dwarf star.

D.) is incorrect. Neutrons stars are collapsed, incredibly dense stars. They are around the size of a city.

Answer:

b

Explanation:

took the test

The value of delta H° for aniline = 6415 Kj/mol

calculation

Step 1: find heat

Q (heat)  =  C (specific heat capacity)  x ΔT (change in temperature)

C= 4.25 kj/c°

ΔT = 69.8-29.5  = 40.3 c°

Q= 4.25 kj/c  x  40.3 c = 171.28 kj

Step 2:  find the moles of aniline

moles  = mass/molar  mass

= 2.49 g/ 93.13 g/mol =0.0267 moles

Step 3:  find delta H

171.28 kj/0.0267 mol = 6415 kj/mol

since the reaction is  exothermic  delta H = 6415 Kj/mol

Answer:

-6.41x10^3

Explanation:

2.49 is 3 significant figures, so your answer should reflect that. Since heat is lost to the surroundings, the reaction is exothermic, and the answer should be negative.

Element X is sodium.

If there is one more shell of electrons, then this means it is one period below.

Since there is one less valence electron, it is one group to the left.

Answer:

29.3 joules

Explanation:

P.E. = mgh

      = 1.5 kg  * 9.81 m/s^2 * 2 m   = 29.3 Joules

The FORMULA for the limiting reagent is [tex]ZnOH_2[/tex].

4.27 grams of reactant remains after the reaction is complete.

The limiting reagent is the reactant that is completely used up in a reaction and thus determines when the reaction stops.

Given data:

Mass of sulfuric acid = 41.0 grams

Molar mass of sulfuric acid = 98.08 g/mol

Mass of zinc hydroxide = 36.5 grams

Molar mass of zinc hydroxide = 99.424 g/mol

Step 1:moles sulfuric acid = mass sulfuric acid / molar mass sulfuric acid

moles sulfuric acid = 41.0 grams / 98.08 g/mol

moles sulfuric acid = 0.41 moles

Step 2: moles of zinc hydroxide

moles zinc hydroxide = 36.5 grams / 99.424 g/mol

moles zinc hydroxide =0.367 moles

Step 3: Calculate limiting reactant

zinc hydroxide is the limiting reactant. It will completely be consumed.

There will remain 0.41 moles - 0.367 moles = 0.043 moles

This is 0.043 moles x 99.424 g/mol

= 4.27 grams

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The type of crude oil that is considered to be the highest quality for gasoline is West Texas Intermediate (Option B).

Oil is a fossil fuel obtained from Earth's crust, which is fundamental nowadays to generate electricity.

West Texas Intermediate is a highly pure and high-type energy source of crude oil used in industry.

In conclusion, the type of crude oil that is considered to be the highest quality for gasoline is West Texas Intermediate.

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Due to the presence of three unpaired electrons, phosphorus is paramagnetic.

Electronic configuration of Phosphorus:-

[Ne] 3S2  3P3

By looking at a substance's electron configuration, one can identify whether or not it has magnetic qualities. If a substance has unpaired electrons, it is paramagnetic; if all of its electrons are paired, it is diamagnetic.

A tiny, positive susceptibility to magnetic fields exists in materials. When exposed to a magnetic field, these materials are only weakly drawn to it; once the external field is removed, they lose their magnetic qualities.

A weak, negative sensitivity to magnetic fields exists in materials. When exposed to a magnetic field, diamagnetic materials are partially repulsed and lose their magnetic properties when the external field is removed.

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The concentration of the solution is 0.17M

The missing question is

What is the concentration of the solution ?

Molarity is the moles of solute in 1 liter of solution.

It is the measure of concentration of a solution in mol/l .

It is given that

5 grams of sodium chloride is dissolved to make 0.5 L of solution

the concentration of the solution

Molecular weight of Sodium Chloride = 58.44 g

58.44 g of NaCl = 1 mol

5g of NaCl = 5/58.44 = 0.086 moles

Molarity = 0.086 / 0.5

Molarity = 0.17 M

The concentration of the solution is 0.17M

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Answer:

boiling water

Explanation:

boiling water produces more severe burns

2Fe(s) + 3Cl₂(g) →2FeCl₃(s)

mol Fe = 15.52 : 56 g/mol = 0.277

mol FeCl₃ = mol Fe = 0.277 (same coefficient)

mass FeCl₃ = 0.277 x 162.2 g/mol = 44.93 g

% yield = 34.5 : 44.93 = 76.79 %

Answer:

C

Explanation:

Marble is the correct answer

Answer:

Ba, Pb, Sn, Se, Cl

Explanation:

The atomic radius increases when going right to left and top to bottom on the periodic table and decreases going the opposite way so I put it in order based on that.

Answer:

Explanation:

To solve problems like this, the very first thing to do is to write out the balanced equation for the process. The reaction is

Zn(s) + HCl(aq) → ZnCl2(aq) + H2(g)

and the balanced equation is

Zn(s) + 2 HCl(aq) → ZnCl2(aq) + H2(g)

So, by examining the stoichiometry, you can see that for every mole of Zn, two moles of HCl will be required. In turn, we need to know the number of moles of Zn is represented by 10.4 g. The molecular weight of Zn is 65.38 g/mol so

moles of Zn = 10.4 g/65.38 g/mol = 0.159 moles

and, twice as many moles of HCl is required so

# of moles of HCl required = 2 * 0.159 = 0.318 moles

Atomic size decreases in a period but the ionization energy and electronegativity increases across a period.

Atomic radius decreases across a period because of nuclear charge increases whereas atomic radius of atoms generally increases from top to bottom within a group because there is again an increase in the positive nuclear charge.

Ionization energy increases when we move from left to right across an period and decreases from top to bottom.

Electronegativity also increases from left to right across a period and decreases from top to bottom.

So we can conclude that atomic size decreases in a period but the ionization energy and electronegativity increases across a period.

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Answer:

a. Physical Chemistry

b.Organic Chemistry

c.Food analysis, a very important branch of analytical chemistry

d. Biochemistry

Explanation:

Answer:

[tex]a. \ \ \ \text{The mass of ethylene is 11.375 g}. \\ \\ b. \ \ \ \text{The volume of water produced is 7.875 ml}.[/tex]

Explanation:

a. According to the chemical equation for the combustion of ethylene, 5

   moles of oxygen are required to react with 2 moles of ethylene, hence

           [tex]m_{C_{2}H_{2}} \ = \ 35 \ \text{g} \ \times \ \displaystyle\frac{1 \ \text{mol}}{\left(2 \times 16 \right) \text{g}} \ \times \ \displaystyle\frac{2 \ \text{mol}}{5 \ \text{mol}} \ \times \ \displaystyle\frac{\left(12 \ \times \ 2 \ + \ 1 \ \times \ 2 \right) \ \text{g}}{1 \ \text{mol}} \\ \\ m_{C_{2}H_{2}} \ = \ 11.375 \ \text{g}[/tex]

b. Similarly, 5 moles of oxygen are required as a reactant to produce 2  

    moles of water, thus

             [tex]m_{H_{2}O} \ = \ 35 \ \text{g} \ \times \ \displaystyle\frac{1 \ \text{mol}}{\left(2 \times 16 \right) \text{g}} \ \times \ \displaystyle\frac{2 \ \text{mol}}{5 \ \text{mol}} \ \times \ \displaystyle\frac{\left(1 \ \times \ 2 \ + \ 16 \right) \ \text{g}}{1 \ \text{mol}} \\ \\ m_{H_{2}O} \ = \ 7.875 \ \text{g}[/tex]

      Given that the density of water is [tex]1.0 \ \text{g ml}^{-1}[/tex], therefore

                                               [tex]\rho_{H_{2}O} \ = \ \displaystyle\frac{m_{H_{2}O}}{V_{H_{2}O}} \\ \\ V_{H_{2}O} \ = \ \displaystyle\frac{m_{H_{2}O}}{\rho_{H_{2}O}} \\ \\ V_{H_{2}O} \ = \ \displaystyle\frac{7.875 \ \text{g}}{1.0 \ \text{g ml}^{-1}} \\ \\ V_{H_{2}O} \ = \ 7.875 \ \text{ml}[/tex]

11.375 g ethylene is consumed if 35.0 grams of oxygen is allowed to react and 7.875 ml of water will be produced when the 35.0 grams of oxygen is allowed to react.

A mole is defined as 6.02214076 ×[tex]10^{23}[/tex] of some chemical unit, be it atoms, molecules, ions, or others. The mole is a convenient unit to use because of the great number of atoms, molecules, or others in any substance.

According to the chemical equation for the combustion of ethylene, 5

moles of oxygen are required to react with 2 moles of ethylene, hence

[tex]m_{_C_2_H_2}[/tex]  [tex]= 35gX \frac{1 mol}{(2 \;X\; 16)g } X \frac{2 mol}{(5\;mol )} X \frac{26g}{1 mol }[/tex]

[tex]m_{_C_2_H_2} = 11.375 g[/tex]

Similarly, 5 moles of oxygen are required as a reactant to produce 2 moles of water, thus

[tex]m_{_H_2_O} = 35gX \frac{1 mol}{(2 \;X\; 16)g } X \frac{2 mol}{(5\;mol )} X \frac{18g}{1 mol }[/tex]

[tex]m_{_H_2_O} = 7.875 g[/tex]

Given that the density of water is [tex]1.0g ml^{-1}[/tex], therefore

[tex]Density = \frac{Mass \;of \;water}{Volume \;of \;water}[/tex]

[tex]Volume \;of \;water = \frac{7.875}{1.0 g ml^{-1}}[/tex]

The volume of water = 7.875 ml

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Answer:

1.) KI

-------> potassium iodide

Potassium (K⁺) is a metal and iodine (I⁻) is a nonmetal. Therefore, when naming, there are no prefixes denoting how many of each element is in the compound. Because potassium is listed first in the compound, it must be the cation. Because iodine is listed second, it must be the anion. Anions in naming have their endings dropped and have the suffix -ide added.

2.) Fe₂O₃

-------> iron(III) oxide

Iron (Fe³⁺) is a metal and oxygen (O²⁻) is a nonmetal. Therefore, when naming, there are no prefixes denoting how many of each element is in the compound. Because iron is listed first, it is the cation and oxygen is the anion. Both of the elements have charges that do not balance each other (denoted by the subscripts). Because iron can have multiple different charges, the charge of iron (+3) should be listed when naming.

3.) (NH₄)₃PO₄

-------> ammonium phosphate

Ammonium (NH₄⁺) and phosphate (PO₄³⁻) are both polyatomic ions. When these ions bond, they also don't have quantity prefixes. Ammonium is the cation and phosphate is the anion. No roman numerals are necessary because the polyatomic ions always have a particular charge.

The concentration terms are molality, normality and mole fraction. Molarity can be used to find out the ionic strength of any solution. Therefore, 0.80g of Fe(NO[tex]_3[/tex])[tex]_3[/tex] are present in a 20.0 mL sample of a 0.500 M solution.

Molarity can be calculated by dividing number of moles of solute by volume of solution in litre. Molarity is affected by temperature. Its unit is mole/liter. It measure the concentration of any solute in a solution.

Mathematically,

Molarity= number of moles of solute/volume of solution in litre (1)

Where,

moles= given weight /by molecular weight

         = w/241.8

Substituting values in equation 1

0.500= (w/241.8)/(20.0 /1000)

w=0.80g

Therefore, 0.80g of Fe(NO[tex]_3[/tex])[tex]_3[/tex] are present in a 20.0 mL sample of a 0.500 M solution.

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The mass in grams of each of the following using dimensional analysis is:

The mass of a substance can be calculated in different ways depending on whether molecules or moles are given.

First, we need to convert atoms/formula units/molecules to moles as follows:

Next, we convert each mole value to mass as follows:

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