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inn [45]
3 years ago
8

An atom has 13 protons and 14 neutrons. what is its mass number?

Chemistry
1 answer:
Artemon [7]3 years ago
5 0

27 is its mass number

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What can be said about a reaction with H = 62.4 kJ/mol and S = 0.145 kJ/(mol·K)?
Zigmanuir [339]
Answer:

At 430.34 K the reaction will be at equilibrium, at  T > 430.34 the reaction will be spontaneous, and at T < 430.4K the reaction will not occur spontaneously.

Explanation:

1) Variables:

G = Gibbs energy
H = enthalpy
S = entropy

2) Formula (definition)

G = H + TS

=> ΔG = ΔH - TΔS

3) conditions

ΔG < 0 => spontaneous reaction
ΔG = 0 => equilibrium
ΔG > 0 non espontaneous reaction

4) Assuming the data given correspond to ΔH and ΔS

ΔG = ΔH - T ΔS = 62.4 kJ/mol + T 0.145 kJ / mol * K

=>  T = [ΔH - ΔG] / ΔS

ΔG = 0 =>  T = [ 62.4 kJ/mol - 0 ] / 0.145 kJ/mol*K = 430.34K

This is, at 430.34 K the reaction will be at equilibrium, at  T > 430.34 the reaction will be spontaneous, and at T < 430.4K the reaction will not occur spontaneously.

3 0
3 years ago
Read 2 more answers
You wish to construct a buffer of pH=7.0. Which of the following weak acids (w/ corresponding conjugate base) would you select?
Alex17521 [72]

Answer:

C.) HOCl Ka=3.5x10^-8

Explanation:

In order to a construct a buffer of pH= 7.0 we need to find the pKa values of all the acids given below

we Know that

pKa= -log(Ka)

therefore

A) pKa of  HClO2 = -log(1.2 x 10^-2)

=1.9208

B) similarly PKa of HF= -log(7.2 x 1 0^-4)= 2.7644

C)  pKa of HOCl= -log(3.5 x 1 0^-8)= 7.45

D) pKa of HCN = -log(4 x 1 0^-10)=  9.3979

If we consider the  Henderson- Hasselbalch equation for the calculation of the pH of the buffer solution

The weak acid for making the buffer must have a pKa value near to the desired pH of the weak acid.

So, near to value, pH=7.0. , the only option is HOCl whose pKa value is 7.45.

Hence, HOCl will be chosen for buffer construction.

3 0
3 years ago
Complete the equation to show how hydrofluoric acid, HF, acts as a Brønsted-Lowry acid in water. Balanced equation:
shepuryov [24]

Answer : The balanced equation is,

HF+H_2O\rightleftharpoons H_3O^++F^-

Explanation :

According to the Bronsted Lowry concept, Bronsted Lowry-acid is a substance that donates one or more hydrogen ion in a reaction and Bronsted Lowry-base is a substance that accepts one or more hydrogen ion in a reaction.

The balanced chemical reaction will be,

HF+H_2O\rightleftharpoons H_3O^++F^-

In this reaction, hydrofluoric acid is act as a Bronsted Lowry-acid because it donate one hydrogen ion to H_2O and H_3O^+ is act as a Bronsted Lowry-base because it accept one hydrogen ion from HF.

8 0
3 years ago
Draw the structure for 1-nitrobutane, making sure to add all non-zero formal charges.
TiliK225 [7]

The molecular structure of 1-nitrobutane is C_{4} H_{9} NO_{2}. The structure of 1-nitrobutane is shown below.

An atom's formal charge would be determined by the covalent model of chemical bonding, which assumes that almost all chemical bonds include equal sharing of electrons among all atoms, regardless their relative electronegativity.

The structure for 1-nitrobutane, making sure to add all non-zero formal charges

There are four kind of molecule present in 1-nitrobutane and they are carbon, hydrogen , nitrogen and oxygen. Nitrogen is bonded with two oxygen atom out of them one oxygen atom is attached with single bond and second oxygen atom is bonded with double bond. Nitrogen has positive charge whereas oxygen has negative charge.

It is a kind of alkane in with nitro group is attached with alkane group.

To know more about 1-nitrobutane

brainly.com/question/25045923

#SPJ4

7 0
1 year ago
7) A block of wood
melamori03 [73]

Answer:

Explanation:

7) A block of wood

has a length of 10.2

cm, a width of 6 cm

and a height of 4.1

cm. The wood has

a total mass of 179

grams. What is the

volume of the

wood and what is

the density of the

wood?

volume = L XW XH=10.2 X 6 X4.1 =250.92cm^3

DENSITY = M/V = 179gm/250.92 cm^3

=0.713 gm/cm^3

5 0
3 years ago
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