Athe gas that siports burning is

B. Why is this number called a "mass” number?

deff fn [24]

Answer:

The mass of the atom depends on the sub atomic particles present in the nucleus of an atom.

That is, the protons and the neutrons.

Electrons are present around the nucleus and the mass is negligible since its mass is very very less.

mass of a proton = $1.673\times10^{-27} kg$

mass of a neutron = $1.675 \times 10^{-27} kg$

mass of an electron = $9.109 \times 10^{-31} kg$

Mass number represents the mass of one particular isotope and it is a whole number for example, $_6 C^{13}$

Mass number is 13 and atomic number is 6 for the carbon isotope C-13.

Atomic mass is different from mass number and it is a fraction since it is the average atomic mass of all the isotopes of an atom.

Atomic mass of C is 12.011 amu which we see in the periodic table is the average atomic mass of isotopes C-12, C-13 and C-14.

7 0

3 years ago

When N,N-Dimethylaniline is treated with bromine, ortho and para products are observed. However, when N,N-Dimethylaniline is tre

lilavasa [31]

Answer:

See explanation below

Explanation:

To get a better understanding watch the picture attached.

In the case of the reaction with Bromine, the -N(CH₃)₂ is a strong ring activator, therefore, it promotes a electrophilic aromatic sustitution, so, in the mechanism of reaction, the lone pair of the Nitrogen, will move to the ring by resonance and activate the ortho and para positions. That's why the bromine wil go to the ortho and para positions, mostly the para position, because the -N(CH₃)₂ cause a steric hindrance in the ortho position.

In the case of the reaction with HNO₃/H₂SO₄, the acid transform the -N(CH₃)₂ in a protonated form, the anilinium ion, which is a deactivating of the ring, and also a strong electron withdrawing, so, the electrophile will go to the meta position instead.

Hope this helps.

6 0

2 years ago

Which of the following acids is the weakest? The acid is followed by its ka value. A) HC2H302, 1.8 * 10-5 B) HIO, 23 x 10-11 OC)

NemiM [27]

Answer:

the weakest acid is B) HIO

Explanation:

pKa = - log Ka

the higher the value of pKa, the lower the dissociation, therefore, an acid will be stronger the lower its pKa.

a) HC2H3O2; Ka = 1.8 E-5

⇒ pKa1 = - Log (1.8 E-5) = 4.745

b) HIO; Ka = 23 E-11

⇒ pKa2 = - Log ( 23 E-11 ) = 9.638

c) HBrO; Ka = 23 E-9

⇒ pKa3 = - Log ( 23 E-9 ) = 7.638

d) HClO; Ka = 2.9 E-8

⇒ pKa4 = - Log ( 2.9 E-8 ) = 7.537

e) HCO2H; Ka = 63 E-5

⇒ pKa5 = - Log ( 63 E-5 ) = 3.200

from the values pKa, we places the acids from the weakest to the least weak:

1) pKa2; HIO (weakest)

2) pKa3

3) pKa4

4) pKa1

5) pKa5

3 0

3 years ago

Your job is to determine the concentration of ammonia in a commercial window cleaner. In the titration of a 25.0 mL sample of th

ruslelena [56]

Answer:

The initial concentration of ammonia is 0.14 M and the pH of the solution at equivalence point is 5.20

Explanation:

To calculate the number of moles for given molarity, we use the equation:

$\text{Molarity of the solution}=\frac{\text{Moles of solute}}{\text{Volume of solution (in L)}}$ .....(1)

Molarity of HCl solution = 0.164 M

Volume of solution = 23.8 mL = 0.0238 L (Conversion factor: 1 L = 1000 mL)

Putting values in equation 1, we get:

$0.164M=\frac{\text{Moles of HCl}}{0.0238L}\\\\\text{Moles of HCl}=(0.146mol/L\times 0.0238L)=0.0035mol$

The chemical equation for the reaction of ammonia and HCl follows:

$NH_3+HCl\rightarrow NH_4^++Cl^-$

By Stoichiometry of the reaction:

1 mole of HCl reacts with 1 mole of ammonia

So, 0.0035 moles of HCl will react with = $\frac{1}{1}\times 0.0035=0.0035mol$ of ammonia

Calculating the initial concentration of ammonia by using equation 1:

Moles of ammonia = 0.0035 moles

Volume of solution = 25 mL = 0.025 L

Putting values in equation 1, we get:

$\text{Initial concentration of ammonia}=\frac{0.0035mol}{0.025L}=0.14M$

By Stoichiometry of the reaction:

1 mole of ammonia produces 1 mole of ammonium ion

So, 0.0035 moles of ammonia will react with = $\frac{1}{1}\times 0.0035=0.0035mol$ of ammonium ion

Calculating the concentration of ammonium ion by using equation 1:

Moles of ammonium ion = 0.0035 moles

Volume of solution = [23.8 + 25] mL = 48.8 mL = 0.0488 L

Putting values in equation 1, we get:

$\text{Molarity of ammonium ion}=\frac{0.0035mol}{0.0488L}=0.072M$

To calculate the acid dissociation constant for the given base dissociation constant, we use the equation:

$K_w=K_b\times K_a$

where,

$K_w$ = Ionic product of water = $10^{-14}$

$K_a$ = Acid dissociation constant

$K_b$ = Base dissociation constant = $1.8\times 10^{-5}$

$10^{-14}=1.8\times 10^{-5}\times K_a\\\\K_a=\frac{10^{-14}}{1.8\times 10^{-5}}=5.55\times 10^{-10}$

The chemical equation for the dissociation of ammonium ion follows:

$NH_4^+\rightarrow NH_3+H^+$

The expression of $K_a$ for above equation follows:

$K_a=\frac{[NH_3][H^+]}{[NH_4^+]}$

We know that:

$[NH_3]=[H^+]=x$

$[NH_4^+]=0.072M$

Putting values in above expression, we get:

$5.55\times 10^{-10}=\frac{x\times x}{0.072}\\\\x=6.32\times 10^{-6}M$

To calculate the pH concentration, we use the equation:

$pH=-\log[H^+]$

We are given:

$[H^+]=6.32\times 10^{--6}M$

$pH=-\log (6.32\times 10^{-6})\\\\pH=5.20$

Hence, the initial concentration of ammonia is 0.14 M and the pH of the solution at equivalence point is 5.20

5 0

2 years ago

PLEASE for the love of god answer these questions for me!!!! It’s urgent.

RideAnS [48]

Igneous rock that forms from magma that cools slowly within Earth’s crust is likely to have larger crystals and a coarse-grained texture.

Igneous rock that forms from lava that cools quickly on Earth’s surface is known as extrusive igneous rock. Another word for extrusive is volcanic.

Because the sample of igneous rock formed on Earth’s surface, it is extrusive. Because it’s composed of mostly light-colored minerals, it is likely felsic.

Because the sample of igneous rock formed within Earth’s crust, it is intrusive. Because it contains a very high concentration of dark-colored, high-density minerals, it is likely ultramafic.

The fact that gabbro is an igneous rock suggests that it was formed from the cooling and crystallization of magma. The fact that it is intrusive means that it formed within Earth’s crust. The fact that it’s mafic suggests that it contains a high concentration of dark-colored, high-density minerals.

4 0

3 years ago

Read 2 more answers