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Answer:

3.11 is the pH of the buffer

Explanation:

The pH of a buffer is obtained using H-H equation:

pH = pKa + log [Conjugate base] / [Weak acid]

Where pH is the pH of the buffer, pKa = -log Ka = 3.14 for the citric buffer and [] could be taken as the moles of each species.

The citric acid,HX (Weak acid), reacts with NaOH to produce sodium citrate, NaX (weak base) and water:

HX + NaOH → H2O + NaX

That means the moles of NaOH added = Moles of sodium citrate produced

And the resulitng moles of HX = Initial moles - Moles NaOH added

Moles HX and NaX:

Moles NaOH = 0.100L * (0.65mol / L) = 0.065 moles NaOH = Moles NaX

Moles HX = 0.300L * (0.45mol / L) = 0.135 moles HX - 0.065 moles NaOH = 0.070 moles HX

Replacing in H-H equation:

pH = 3.14 + log [0.065mol] / [0.070mol]

pH = 3.11 is the pH of the buffer

Answer:

True.

Explanation:

Yes, analyses of enzymes found in the blood are used as indicators of tissue damage in the heart, liver, muscle etc has occurred. This leakage of enzymes into the bloodstream tells us whether the tissue is damaged or not. Lactate dehydrogenase is a type of enzyme which is used as indicator which is responsible for the interconverts lactate and pyruvate. The concentration of this enzyme in the blood tells us about tissue damage.

Answer:

a. True

Explanation:

The co enzyme used for this reaction is NADH+, here H+ acts as co substrate.

This is required to find the tissue damage that has occurred in our body which resulted in leakage of cellular enzymes into the bloodstream.

This coenzyme is used for conversion of lactose dehydrogenase.

Answer:

~4,317.5 moles of Silicon

Explanation:

Using Avogadro's contant we know that:

1mole = 6.022 x 10^23 atoms

So,to calculate the number of moles in 2.60 x 10^27 atoms of Silicon:

=(2.60 x 10^27 x 1)/(6.022 x 10^23)

~4,317.5 moles of Silicon

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Answer:

There are 0.195 moles.

Explanation:

1 mol of any gas under STP (meaning 1 atm and 273 K) will occupy 22.4 liters.

With the information above in mind, we can calculate how many moles will occupy 4.38 liters:

In 4.38 liters of a gas at STP there will be 0.195 moles.

Answer:

5 Acids

Chemical

- Hydrochloric acid in gastric juice

- Sulphuric acid

- Nitric acid

- Uric acid

- Acetic acid

Household

- Vinegar

- Lemon

- Milk

- Batteries

- Soft drinks

5 Alkali

Household

- Dishwashwer soaps

- Detergents

- Toothpaste

- Oven cleaner

- Alkaline batteries

- Sodium bicarbonate

Chemicals

- Sodium hydroxide or lye

- Calcium carbonate (limestone)

- Ammonium hydroxide

- Calcium hydroxide

Answer:

[tex](24 \times 2) \: g \: of \: magnesium \: reacts \: with \: (16 \times 2) \: g \: of \: oxygen \\ 2.64 \: g \: of \: magnesium \: will \: react \: with \: ( \frac{2.64 \times 16 \times 2}{24 \times 2} ) \: g \\ = 1.76 \: g \: of \: oxygen[/tex]

Answer:

Hello, I was doing this and from my caluclations it should be :

Explanation:

3 Moles.

The three moles of MgCO3 are present in 252.939 grams of MgCO3.

So, option B is correct one .

The molar mass of substance is equal to mass of one mole of  that substance.

Example: Molar mass of MgCO3 is equal to mass of one mole of MgCO3.

Molar mass of Mg = 24.305 u

Molar mass of C = 12.011 u

Molar mass of O = 15.999 u

Molar mass of MgCO3 = Molar mass of Mg + Molar mass of C + Molar mass of O*3

Molar mass of MgCO3 = 24.305 + 12.011  +  15.999 * 3

Molar mass of MgCO3 = 84.3139 gram

Molar mass of  MgCO3 contain  84.3139 gram

So, 252.939 grams of MgCO3 = 252.939 grams/84.3139 gram

252.939 grams of MgCO3 = 2.999 moles

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Answer:

A. London dispersion

Explanation:

London dispersion force is a temporary attractive force that results when the electrons in two adjacent atoms occupy positions that make the atoms form temporary dipoles. 

The intermolecular forces are due to the attraction between temporary dipoles, and their induced temporary dipoles are the type of  London dispersion force. Therefore, option A is correct.

When the electrons in two nearby atoms occupy positions that cause the atoms to temporarily form dipoles, the consequence is the London dispersion force, a transient attractive force. The term "induced dipole-induced dipole attraction" is frequently used to describe this effect.

The electron density of a molecule is redistributed towards another molecule because the electrons in nearby molecules "flee" when they repel one another. This is typically explained as the instantaneous production of attracted dipoles.

The material's atomic or molecular weight affects the London dispersion forces. More electrons and stronger London forces are present in heavier atoms or molecules. They are therefore more difficult to melt or boil.

Thus, option A is correct.

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Explanation:

The boiling point of alcohols also increase as the length of hydrocarbon chain increases

The boiling point of alcohols also increase as the length of hydrocarbon chain increases.

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Answer:

Evaporation

Explanation:

Water in the ocean, rivers, lakes, etc. is part of the hydrosphere, and when that water evaporates it enters the atmosphere

We know that [OH⁻] * [H⁺] = 10⁻¹⁴

plugging the value of [H⁺]

[OH⁻] * 1.2 * 10⁻³ = 10⁻¹⁴

[OH⁻] = 10⁻¹⁴ * (10³/1.2)

[OH⁻] = 833.3 * 10⁻¹⁴

[OH⁻] = 8.33 * 10⁻¹²

+HF is the answer

Explanation:

Explanation:

H=mc×∆©

9.86=m×0.902×(30.5-23.2)

m=1.5

Explanation:

The specific heat of a substance is the amount of heat required to raise the temperature of 1 gram of the substance by 1 degree Celsius. The formula for calculating the heat absorbed or released by a substance is `q = mcΔT`, where `q` is the heat absorbed or released, `m` is the mass of the substance, `c` is the specific heat of the substance, and `ΔT` is the change in temperature.

In this case, we can use this formula to solve for the mass of the aluminum sample. We know that `q = 9.86 J`, `c = 0.902 J/g°C`, and `ΔT = 30.5°C - 23.2°C = 7.3°C`. Plugging these values into the formula, we get:

`9.86 J = m * 0.902 J/g°C * 7.3°C`

Solving for `m`, we find that the mass of the aluminum sample is approximately `1.5 g`, rounded to 2 significant figures.

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Answer:

true

Explanation:

Endo means inside

but exo means outside

an Endo thermic reaction sounds like it wouldn't be the one to give off heat, so it might be storing heat.

Answer:

T = 82 K

Explanation:

The computation of the final temperature is shown below;

Given that

T_0 denotes the initial temperature of the gas i.e. 74 K

T denotes the final temperature of the gas = ?

n denotes number of moles of monoatomic gas i.e. 1.00 mol

R denotes universal gas constant = 8.314

c denotes the heat capacity at constant volume i.e.

= (1.5) R = (1.5) (8.314)

= 12.5

Q denotes the Amount of heat absorbed i.e 100 J

We know that

Amount of heat absorbed is provided as

Q = n c (T - T_0)

100 = (1) (12.5) (T - 74)

T = 82 K

Answer: There are [tex]16.14 \times 10^{23}[/tex] atoms of hydrogen are present in 40g of urea, [tex](NH_{2})_{2}CO[/tex].

Explanation:

Given: Mass of urea = 40 g

Number of moles is the mass of substance divided by its molar mass.

First, moles of urea (molar mass = 60 g/mol) are calculated as follows.

[tex]Moles = \frac{mass}{molar mass}\\= \frac{40 g}{60 g/mol}\\= 0.67 mol[/tex]

According to the mole concept, 1 mole of every substance contains [tex]6.022 \times 10^{23}[/tex] atoms.

So, the number of atoms present in 0.67 moles are as follows.

[tex]0.67 mol \times 6.022 \times 10^{23} atoms/mol\\= 4.035 \times 10^{23} atoms[/tex]

In a molecule of urea there are 4 hydrogen atoms. Hence, number of hydrogen atoms present in 40 g of urea is as follows.

[tex]4 \times 4.035 \times 10^{23} atoms\\= 16.14 \times 10^{23} atoms[/tex]

Thus, we can conclude that there are [tex]16.14 \times 10^{23}[/tex] atoms of hydrogen are present in 40g of urea, [tex](NH_{2})_{2}CO[/tex].

Answer:

Fraction ionic = 0.43

Explanation:

To solve this question, we must, as first, find the fraction of the bond that is covalent using the equation:

Fraction Covalent = exp (-0.25*(Enitride - EAl)²)

Fraction covalent = exp (-0.25*(3.0- 1.5)²)

Fraction covalent = exp (-0.25*2.25)

Fraction covalent = exp (-0.5625)

Fraction covalent = 0.57

As:

1 = Fraction Covalent + Fraction Ionic:

Fraction ionic = 1 - 0.57

Fraction ionic = 0.43

Answer:

The heat capacity of the metal underneath the gold is 0.431 J/g°C

Explanation:

Using the formula as outlined in the image:

Q = m × c × ∆T

Where;

Q = amount of heat energy (J)

m = mass of substance (g)

c = specific heat capacity (J/g°C)

∆T = change in temperature (°C)

According to the information in this question;

Q = 503.9J

m = 23.02g

c = ?

∆T = 74°C - 23.2°C = 50.8°C

Using Q = m × c × ∆T

c = Q ÷ m∆T

c = 503.9 ÷ (23.02 × 50.8)

c = 503.9 ÷ 1169.42

c = 0.431 J/g°C

From the above heat capacity of the metal underneath the gold, it is obvious that the metal is not pure gold (c = 0.129J/g°C)

Answer:

XeF4                  True

[PdCl4]2−           True

naphthalene      True

Furan                  False

C4H4O               False  

Explanation:

From the given information:

Only XeF4;  [PdCl4]2−;  naphthalene are true. This is because their molecules contain -nC₂ axis which is perpendicular to the Cn axis. The image attached below shows the structural formula of each compound, there below, we can see that Furan only possesses one C₂ axis but not -nC₂ ⊥ C₂.

The main function of nucleic acid is It stores lipids inside the proteins.

Nucleic acids are large biomolecules that play essential roles in all cells and viruses. A major function of nucleic acids involves the storage and expression of genomic information. Deoxyribonucleic acid, or DNA, encodes the information cells need to make proteins. A related type of nucleic acid, called ribonucleic acid (RNA), comes in different molecular forms that play multiple cellular roles, including protein synthesis. 

Nucleic acids are made of nitrogen-containing bases, phosphate groups, and sugar molecules. Each type of nucleic acid has a distinctive structure and plays a different role in our cells. Researchers who first explored molecules inside the nucleus of cells found a peculiar compound that was not a protein or a lipid or a carbohydrate. It was new.  The discovery of this molecule — nuclein, which upon further understanding became nucleic acid — set in motion the eventual discovery of DNA.

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When the concentration of the HCl is varied, the color of the solution is changed as the equilibrium position moves to the left or right.

The term equilibrium in a chemical reaction connotes that the forward and the revers reactions proceed at the same rate. Let us note that Co(H2O)6^2+ is pink in color while  CoCl4^2– is blue in color.

As such, when the concentration of the HCl is varied, the color of the solution is changed as the equilibrium position moves to the left or right.

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Answer:

a endothermic, absorbed

Answer:

119.5 J

Explanation:

First we calculate the temperature difference:

Then we can calculate the heat released by using the following formula:

Where q is the heat, Cp is the specific heat, ΔT is the temperature difference and m is the mass.

We input the data:

Answer:  the area of the telescope lens is \textit{0,08507 ft}

Explanation: Happy I could help!

Answer:

9g

Explanation:

moles O2 = mass / Mr = 12 / 2(16.0) = 0.375

ratio O2 : NO = 5:4

moles NO produced = 0.375 * 4/5 = 0.3

mass NO = Mr * mol = (14.0+16.0) * 0.3 = 9g

The Grams of NO is produced if 12g of O2 is combined with excess ammonia is 80 gram.

The full form of NO is nitrogen oxide Nitrogen belong to the 15th group of the periodic table with molar mass of 14 and oxygen belong to the 16th group of the periodic table.

In the given their are 4 molecules of each nitrogen and oxygen and mass of O2 is given whereas, mass of nitrogen for 4 molecule will be 56 gram.

Grams of NO = 14 × 4 + 12 × 2

Grams of NO = 80 grams.

Therefore, the mass of NO for the given reaction is combined with excess ammonia is 80 gram.

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Answer:

El cloruro de litio se utiliza para fabricar litio metálico. El cloruro de litio se funde y electroliza. Esto produce litio metálico líquido.

Explanation:

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Answer:

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Explanation:

Answer:

See Explanation

Explanation:

Given that;

N/No = (1/2)^t/t1/2

Where;

No = amount of radioactive isotope originally present

N = A mount of radioactive isotope present at time t

t = time taken

t1/2 = half life

N/1000=(1/2)^3/6

N/1000=(1/2)^0.5

N = (1/2)^0.5 * 1000

N= 707 unstable nuclei

Since the value of the initial activity of the radioactive material was not given, the activity of the radioactive material after three months is given by;

Decay constant = 0.693/t1/2 = 0.693/6 months = 0.1155 month^-1

Hence;

A=Aoe^-kt

Where;

A = Activity after a time t

Ao = initial activity

k = decay constant

t = time taken

A = Aoe^-3 *0.1155

A=Aoe^-0.3465

The question is incomplete, the complete question is:

Nitrogen and fluorine react to form nitrogen fluoride according to the chemical equation:

[tex]N_2(g)+3F_2(g)\rightarrow 2NF_3(g)[/tex]

A sample contains 19.3 g of [tex]N_2[/tex] is reacted with 19.3 g of [tex]F_2[/tex]. Now we need to find the amount of [tex]NF_3[/tex] that can be formed by the complete reactions of each of the reactants.

If all of the [tex]N_2[/tex] was used up in the reaction, how many moles of [tex]NF_3[/tex] would be produced?

Answer: 1.378 moles of [tex]NF_3[/tex] are produced in the reaction.

Explanation:

The number of moles is defined as the ratio of the mass of a substance to its molar mass.

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]       ......(1)

Limiting reagent is defined as the reagent which is completely consumed in the reaction and limits the formation of the product.

Excess reagent is defined as the reagent which is left behind after the completion of the reaction.

In the given chemical reaction, [tex]N_2[/tex] is considered as a limiting reagent because it limits the formation of the product and it was completely consumed in the reaction.

We are given:

Mass of [tex]N_2[/tex] = 19.3 g

Molar mass of [tex]N_2[/tex] = 28.02 g/mol

Putting values in equation 1:

[tex]\text{Moles of }N_2=\frac{19.3g}{28.02g/mol}=0.689mol[/tex]

For the given chemical reaction:

[tex]N_2(g)+3F_2(g)\rightarrow 2NF_3(g)[/tex]

By the stoichiometry of the reaction:

1 mole of [tex]N_2[/tex] produces 2 moles of [tex]NF_3[/tex]

So, 0.689 moles of [tex]N_2[/tex] will produce = [tex]\frac{2}{1}\times 0.689=1.378mol[/tex] of [tex]NF_3[/tex]

Hence, 1.378 moles of [tex]NF_3[/tex] are produced in the reaction.