How many joules of heat are absorbed when 10.00 grams of water is completely vaporized at its boiling

What is the ph of a solution of 0.550 m k2hpo4, potassium hydrogen phosphate?

Solnce55 [7]

We assume that we have Ka= 4.2x10^-13 (missing in the question)
and when we have this equation:
H2PO4 (-) → H+ + HPO4-
and form the Ka equation we can get [H+]:
Ka= [H+] [HPO4-] / [H2PO4] and we have Ka= 4.2x10^-13 & [H2PO4-] = 0.55m
by substitution:
4.2x10^-13 = (z)(z)/ 0.55
z^2 = 2.31x 10^-13
z= 4.81x10^-7
∴[H+] = 4.81x10^-7
when PH equation is:

PH= -㏒[H+]
= -㏒(4.81x10^-7) = 6.32

3 0

3 years ago

A magnesium ion, Mg2+, is formed from a magnesium atom, Mg.

konstantin123 [22]

Answer:

The correct row is B.

Explanation:

The formation of the magnesium ion, Mg²⁺, comes from the removal of 2 electrons from the valence shell of the magnesium atom. Since the remotion is of electrons, the nucleus of the atom remains the same, so the number of protons and the number of neutrons does not change.

If the number of proton change, then the atom also change, since the identity of an atom is related to the atomic number which is the same to the proton number.

Now, if the number of neutrons changes, then we would be in the presence of an isotope of the magnesium atom.

Therefore, the correct row is B.

I hope it helps you!

5 0

3 years ago

The speed of light(c) is 3.00X10^8 m/s the frequency(v) of a given wave is 2.43X10^8 Hz. What is the wavelenght (λ)

nasty-shy [4]

Frequency = speed of light/ wavelength of photon. wavelength = speed of light/frequency = 3 x 10^8 / 2.43 x 10^8= 1.23m

7 0

3 years ago

State which of the following set of quantum number would be possible and which would be permissible for an electron in an atom.

raketka [301]

Answer:

The correct option is: e) n=4, l=3, $m_{l}$ = - 2 , $m_{s}$ = - 1/2

Explanation:

The four quantum numbers that describe the electrons in an atom are: The principal: n, azimuthal: l, magnetic: m, and spin: s.

For a given electron, the values of the quantum numbers should be in the given range- principal quantum number: n ≥ 1;

azimuthal quantum number: 0 ≤ l ≤ n − 1;

magnetic quantum number: −l ≤ $m_{l}$ ≤ +l;

spin quantum number: −s ≤ $m_{s}$ ≤ +s

Now, for n= 4,

The value of l: 0 to n − 1 = 0 to 3 = 0, 1, 2, 3

The value of $m_{l}$ for l= 3 : -3 to +3 = -3, -2, -1, 0, +1, +2, +3

The value of $m_{s}$ : -1/2, +1/2

Therefore, the given set of quantum numbers: n=4, l=3, $m_{l}$ = - 2 , $m_{s}$ = - 1/2; are possible and permissible for an electron in an atom.

5 0

3 years ago

Replacing standard incandescent light bulbs with energy-efficient compact fluorescent lightbulbs can save a lot of energy. Calcu

EleoNora [17]

Answer:

a) 1512000 Joules

b) 5040 seconds = 84 minutes = 1.4 hours

Explanation:

Power saved y replacing bulbs = 60-18 = 42 W = 42 J/s

Time the bulb is used for = 10 hours

Energy saved during this time

42×10×60×60 = 1512000 Joules

Saved energy by replacing standard incandescent lightbulbs with energy-efficient compact fluorescent lightbulbs in 10 hours is 1512000 Joules

b) Power the plasma TV uses = 300 W = J/s

\frac{1512000}{300}=5040\ s3001512000=5040 s

Time a plasma TV can be used for with the saved energy is 5040 seconds = 84 minutes = 1.4 hours.

3 0

2 years ago