Nicotinic acid, HC6H4NO2, is a B vitamin. It is also a weak acid with Ka = 1.4 × 10-5. Calculate [H+] and the pH of a 0.041 M solution of HC6H4NO2.

Answer:2m

Explanation:

4/2=2

The wavelength will be "2 m".

Given values are:

Frequency,

Speed,

As we know,

→ [tex]Frequency(f) = \frac{Speed (v)}{Wavelength (\lambda)}[/tex]

or,

→                     [tex]\lambda = \frac{v}{f}[/tex]

By substituting the values, we get

→                        [tex]=\frac{4}{2}[/tex]

→                        [tex]= 2 \ m[/tex]

Thus the above response is correct.

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Answer:

pH = 11

Explanation:

The equilibrium of a weak base as NaCN in water is:

NaCN(aq) + H₂O(l) ⇄ OH⁻(aq) + Na⁺(aq) + HCN(aq)

And kb, the equilibrium constant, is:

Kb = [OH⁻] [HCN] / [NaCN]

Where Kb of NaCN is 2.04x10⁻⁵

In the beginning, the [NaCN] is 0.050mol / L = 0.050M.

Both [OH⁻] and [HCN] are produced from this equilibrium, and its concentration is X, that is:

2.04x10⁻⁵ = [X] [X] / [0.050M]

1.02x10⁻⁶ = X²

X = 1x10⁻³ = [OH⁻]

As pOH = - log [OH⁻]

pOH = 3.00

And pH = 14 - pOH

the answer is atomic numbers

Answer:

atomic numbers

Explanation:

In order for two atoms to be different, they have to have a different number of protons. Protons are represented by the atomic number. Thus, atoms of two DIFFERENT elements must have different atomic numbers.

I took the test and got 100%

Hope this helps!

Answer:D

Explanation: in molecular solids, one factor that determines the strength of intermolecular forces is the mass of the molecules. Since all of these compounds only contain hydrogen and carbon we don’t have to worry about their polarities as they are all the same. Inter molecular forces tend to be stronger when the molecular weight is greater since paraffin wax is the only solid at room temperature it has the highest melting point

Answer: Your Answer Is D. Paraffin wax

Explanation:Hope This Helps!

Answer:

Mass of the unknown acid is 4.0g

Explanation:

The determine the molar mass of the unknown acid, the steps below can be followed

Firstly, determine the concentration of the acid, the formula below can be used;

ConcA × Va/ConcB × Vb = Na/Nb

Where ConcA is the concentration of the unknown acid

ConcB is the concentration of the NaOH base

Va is the volume of acid and Vb is the volume of base

Since, the titration was said to have reached an equivalent point, it means the number of moles of the acid (Na) was equal to the number of moles of the base (Nb) and thus both will be assumed to be 1

Thus

ConcA × 250/0.13 × 6.6 = 1/1

ConcA = 0.13 × 6.6/250

ConcA = 0.003432M

Then, determine the actual number of moles (n) of the unknown acid used,

ConcA = no of moles of acid/volume of acid (in dm³ or L)

To convert mL to L, we divide by 1000

Hence, 250ml = 0.25L

0.003432 = n/0.25

n = 0.003432 × 0.25

n = 0.01373 moles

To determine the molar mass;

n = mass/molar mass

The mass was given in the question to be 0.055g

Thus

0.01373 = 0.055/molar mass

molar mass = 0.055/0.01373

molar mass = 4.0g

a = 7.5 m/s²

Hi there !

Newton's second law

F = m×a => a = F/m

1 N = 1kg·m/s²

a = (75kg.m/s²)/10kg

= 7.5 m/s²

Good luck !

Answer:

A family is a vertical column .

The elements in a family have similar chemical properties.

Answer:

NaCl(aq)

Explanation:

Nacl(aq) is an electrolyte when it melts and it conducts electricity. This is due to the fact that when it is in solution, it dissociates to be Na+ and Cl-. These ions are conductors of electricity. It conducts electricity because of the movements and also the discharge of ions. CH3OH(aq) is not a conductor of electricity therefore the first option is the answer.

Answer:

Geology is the world... Elements make it up

Explanation:

Answer:

A lot of the elements are found in rocks, minerals, and well since they are elements make they make up everything on earth.

Explanation:

Answer:

Explanation:

Iodine is the most flexible of the atoms in Group 17 of the periodic table. It can have more than 1 charge, especially when combined with oxygen. The answer that you are expected to give, I think is C. Iodine's dominant charge is - 1

Answer:

See explanation

Explanation:

What I have written in the image attached is called a nuclear equation. It differs from a chemical reaction equation in the sense that it involves transformations that occur in the nucleus of atoms.

The nuclear equation must be balanced. This means that the mass and charge on both sides of the reaction equation must be the same.

On the left hand side the U-235 interacts with a neutron. The total mass on the left hand side is 236 while the total charge is 92. If we sum up the masses and charges of Ba and Kr, we also get a total of 236 mass units and a charge of 92.

Hence the other nucleus is barium-141

Answer:

True

Explanation:

Because atoms with the same number of valence electrons react in similar ways with other elements.

Answer:

See explanation

Explanation:

The compound ClO2 has 19 valence electrons.  ClO2 is a bent molecule with tetrahedral electron pair geometry but has two  lone pairs of electrons. This is indicated by the presence of four electron pairs on the outermost shell of the central atom.

The molecule has an odd number of valence electrons, hence, it is generally regarded as a paramagnetic radical. None of the proposed Lewis structures for the molecule is satisfactory because none of them obeys the octet rule.

From the images attached, one can easily see that the electron dots around the oxygen and chlorine atoms does not satisfy the octet rule in all the resonance structures shown.

Answer:

I literally got this from google.

Explanation:

In ordinary air, sodium metal reacts to form a sodium hydroxide film, which can rapidly absorb carbon dioxide from the air, forming sodium bicarbonate. ... In a comparatively dry atmosphere, sodium burns quietly, giving off a dense white caustic smoke, which can cause choking and coughing.

Happy almost Halloween! :)

Answer:

c,a,b,d

Explanation:

Answer:

a.  very acidic

Explanation:

A solution with a pH of 1.6 would be described as a very acidic solution.

The pH scale is a convenient scale for expressing the level of acidity or alkalinity of aqueous solutions.

The scale ranges from 1 to 14 in which case 1 is the lower limit and 14 the upper limit.  

Answer:

A

Explanation:

Using the equation above, the dipole moment is calculated to be 1.85 D by multiplying the distance between the oxygen and hydrogen atoms by the charge difference between them and then finding the components of each that point in the direction of the net dipole moment (the angle of the molecule is 104.5˚).

Answer: The glass cup falling

Explanation:

It didnt change chemically, only its physical appearance

We know,

[tex]\Delta H_{I_2(g)}=62.438\ KJ/mol\\\\\Delta H_{Cl_2(g)}= 0.0\ KJ/mol\\\\\Delta H_{ICl(g)}=17.78\ KJ/mol[/tex]

For given reaction, [tex]I_2(g)+Cl_2(g)\ -->\ 2ICl(g)[/tex]

[tex]\Delta H_{rxn}=2\Delta H_{ICl(g)}-\Delta H_{I_2(g)}-\Delta H_{Cl_2(g)}\\\\\Delta H_{rxn}=2(17.78)-0-62.438\ KJ/mol\\\\\Delta H_{rxn}=-26.878\ KJ/mol[/tex]

For , 2.41 moles of [tex]I_2[/tex] :

[tex]\Delta H_{rxn}=2.41\times (-26.878)\ KJ\\\\\Delta H_{rxn}=-64.78\ KJ[/tex]

We know :

[tex]\Delta S = -\dfrac{\Delta H_{rxn}}{T}\\\\\Delta S = -\dfrac{-64.78}{298}\ KJ/K\\\\\Delta S =-0.21738 \ KJ/K\\\\\Delta S=-217.38\ J/K[/tex]

Hence, this is the required solution.

Answer:

I think it's A and D

Explanation:

I'm not sure if it's right

Answer:

The answer is B and D

Explanation:

trust fr

Answer:  D) 11

Explanation:

We have 1 iron atom (the Fe)

We have 5 carbon (denoted [tex]C_5[/tex])

We have 5 oxygen atoms (denoted [tex]O_5[/tex])

So we have 1+5+5 = 11 atoms in this compound.

In one formula unit of  [tex]\rm FeC_5O_5[/tex], the number of atoms of oxygen has been 5. Thus , option B is correct.

Formula unit has been the empirical representation of the chemical compound. The formula has been responsible to deliver the information about the number of atoms of each elements present in the sample.

The given compound has been [tex]\rm FeC_5O_5[/tex]. The formula has subscript with each element representing the number of atoms.  The atoms of each element has been:

The number of atoms of oxygen present in one formula unit of [tex]\rm FeC_5O_5[/tex] has been 5. Thus , option B is correct.

For more information about the formula unit, refer to the link:

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Answer:

immiscible liquids

Explanation:

When two liquids are to be used for the purpose of recrystallization the both liquids must be miscible with each other in all proportions.

This implies that, if two liquids are immiscible, it will be difficult for the mixture to be useful in recrystallization.

Water and hexane are immiscible because water is a polar solvent and hexane is a non polar solvent.

Water is miscible with ethanol because ethanol contains polar -OH groups that interact effectively with water leading to miscibility of ethanol with water in all proportions.

Answer:

The answer is B(scale)

Explanation:

Since the question asked about a range, the scale would be the most logical answer since scales are used to measure.

Answer:

the answer is C.

Explanation:

Answer:

an insoluble substance which is the main constituent of plant cell walls and of vegetable fibers such as cotton. It is a polysaccharide consisting of chains of glucose monomers.

Cellulose is the main substance in the walls of plant cells, helping plants to remain stiff and upright. Humans cannot digest cellulose, but it is important in the diet as fibre. Fibre assists your digestive system – keeping food moving through the gut and pushing waste out of the body.

Explanation:

Answer:

Hello! The main chemical component in cell walls is a complex carbohydrate called cellulose. Cellulose is made of thousands of sugar molecules linked end to end. It is extremely durable, which makes it useful for paper, linen, and cotton products. So the answer to your question is: Cellulose is a very complex carbohydrate that is found in plant walls. In fact, it is the basic structural component in plant walls.

Explanation:

Hope this helped!

Answer:

The answer is "Option a".

Explanation:

Multiply the mass of the solutions by 3.17% to get the mass of [tex]BaCl_2[/tex]:

[tex]\to 427 \ g \times 0.0317 = 13.56\ g[/tex]

Divide this mass with BaCl2's molecular concentration to acquire the mole ratio:  

[tex]molar mass = 208.24 \frac{g}{mol}\\\\moles = \frac{13.56}{208.24} = 0.065 \ moles \\\\[/tex]

                       [tex]= 6.5 \times 10^{-2} \ moles[/tex]

A 427 g sample is 3.17% by mass barium chloride contains 6.5 × 10⁻² moles of BaCl₂.

A 427 g sample is 3.17% by mass barium chloride, that is, there are 3.17 g of barium chloride per 100 g of sample.

The mass of barium chloride in 427 g of the sample is:

[tex]427gSample \times \frac{3.17gBaCl_2}{100gSample} = 13.5gBaCl_2[/tex]

We can calculate the number of moles in 13.5 g of barium chloride using its molar mass (208.23 g/mol).

[tex]13.5 g \times \frac{1mol}{208.23g} = 6.5 \times 10^{-2} mol[/tex]

A 427 g sample is 3.17% by mass barium chloride contains 6.5 × 10⁻² moles of BaCl₂.

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Answer:

The percentage yield of copper will exceed 100%

Explanation:

In the presence of impurities, the percentage yield of a substance usually exceeds 100%.

This implies that, when the unreacted zinc impurity is not removed from the reaction mixture and the percentage yield of copper is calculated, the actual yield will become greater than the theoretical yield thereby making the percentage yield of copper to be above 100%

Answer:

the bike will go down 5 N

Answer:

0.0181 mol H

Explanation:

Step 1: Given data

Moles of water (H₂O) formed during the analysis: 0.00905 mol H₂O

Step 2: Calculate the amount (mol) H in 0.00905 mol H₂O

According to the chemical formula of water, the molar ratio of water to hydrogen is 1:2, that is, there are 2 moles of H per 1 mole of H₂O. We will use this conversion factor to calculate the moles of H in 0.00905 moles of H₂O.

0.00905 mol H₂O × (2 mol H/1 mol H₂O) = 0.0181 mol H

Answer:

The wood sample has an age of approximately 22800 years.

Explanation:

The Becquerel ([tex]Bq[/tex]) is a SI unit which describes radioactive activity related to decay of radioactive isotopes, which is equivalent to [tex]\frac{1}{s}[/tex]. The decay of radioactive isotope is described by the following ordinary differential equation:

[tex]\frac{dN}{dt} = -\frac{N}{\tau}[/tex] (Eq. 1)

Where:

[tex]\frac{dN}{dt}[/tex] - Disintegration rate, measured in [tex]\frac{1}{s}[/tex].

[tex]N[/tex] - Amount of remaining radioactive nuclei, dimensionless.

[tex]\tau[/tex] - Time constant, measured in seconds.

By integration the solution of this differential equation is obtained:

[tex]\int {\frac{dN}{N} } = -\frac{t}{\tau}\int dt[/tex]

[tex]\ln N = -\frac{t}{\tau} + C[/tex]

[tex]N(t) = N_{o}\cdot e^{-\frac{t}{\tau} }[/tex] (Eq. 2)

Let [tex]N_{1}[/tex] and [tex]N_{2}[/tex] different disintegration rates for Carbon-14 samples, so that:

[tex]N_{1} = N_{o} \cdot e^{-\frac{t_{1}}{\tau} }[/tex] (Eq. 3)

[tex]N_{2} = N_{o}\cdot e^{-\frac{t_{2}}{\tau} }[/tex] (Eq. 4)

If we divide (Eq. 4) by (Eq. 3), then:

[tex]\frac{N_{2}}{N_{1}} = \frac{N_{o}\cdot e^{-\frac{t_{2}}{\tau} }}{N_{o}\cdot e^{-\frac{t_{1}}{\tau} }}[/tex]

[tex]\frac{N_{2}}{N_{1}} = e^{-\frac{1}{\tau}\cdot (t_{2}-t_{1}) }[/tex] (Eq. 5)

If [tex]\Delta t = t_{2}-t_{1}[/tex], we proceed to clear that variable:

[tex]\ln \frac{N_{2}}{N_{1}} = -\frac{1}{\tau}\cdot \Delta t[/tex]

[tex]\Delta t = -\tau\cdot \ln \frac{N_{2}}{N_{1}}[/tex] (Eq. 6)

Time constant is also a function of half-life ([tex]t_{1/2}[/tex]), measured in seconds:

[tex]\tau = \frac{t_{1/2}}{\ln 2}[/tex]

If [tex]t_{1/2} = 1.798\times 10^{11}\,s[/tex], [tex]N_{1} = 14\,\frac{1}{s}[/tex] and [tex]N_{2} = 0.875\,\frac{1}{s}[/tex],  the age of the wood sample is:

[tex]\tau = \frac{1.798\times 10^{11}\,s}{\ln 2}[/tex]

[tex]\tau = 2.594\times 10^{11}\,s[/tex]

[tex]\Delta t = -(2.594\times 10^{11}\,s)\cdot \ln \left(\frac{0.875\,\frac{1}{s} }{14\,\frac{1}{s} } \right)[/tex]

[tex]\Delta t \approx 7.192\times 10^{11}\,s[/tex]

[tex]\Delta t \approx 22805.682\,yr[/tex]

The wood sample has an age of approximately 22800 years.