All categories

3 years ago

What is the mass of 1.7 × 1023 atoms of zinc (Zn)?

Chemistry

1 answer:

Rudiy273 years ago

8 0

Number of moles is defined as the ratio of given mass in g to the molar mass.

The mathematical formula is:

Number of moles = $\frac{given mass in g}{molar mass}$ (1)

Number of zinc atoms is equal to $1.7\times10^{23}$ , by Avogadro number, number of moles can be calculated.

As, 1 mol= $6.022\times10^{23}$ atoms, hence,

$1.7\times10^{23}\times\frac{1 mol}{6.022\times10^{23} }$

= 0.2822 mol

Now, from formula (1), calculate mass in g (molar mass of zinc = 65.4 g/mol)

0.2822 mol = $\frac{mass in g}{65.4 g/mol}$

mass in g = ${0.2822 mol \times 65.4 g/mol$

= 18.45588 g

Thus, by rounding off the above number, it will come near about 19 g approximately.

Hence, option (C) is the correct answer.

You might be interested in

Starting with 250 mL of a 0.250 M solution of HBr; a) Calculate the initial pH of the solution.b) Calculate the pH after adding

maxonik [38]

Answer:

pH = 0.602

pH = 1.5

pH = 7

pH = 12.1

Explanation:

a ) To calculate the pH, use the following equation:

pH = -log [H+]

Hbr is a strong acid, so the [H+] concentration can be calculated as follow:

[HBr] = 0.250 M

As acid Hbr:

Hbr = H+ + Br-

As strong acid HBr dissociates at all, so

[HBr] = [H+] = 0.250 M

So the pH:

pH = -log [0.250 M] = 0.602

b) Calculate the pH after adding 250 mL of 0.125M NaOH

In this point, the reactions starts:

HBr + NaOH = H2O + NaBr

- First, we gonna find the mol of each reactant:

HBr:

mol = [M] × L

mol = 0.250 M × 0.250 L

mol = 0.0625 mol HBr

NaOH:

mol = [M] × L

mol = 0.125 M × 0.250L

mol = 0.03125 mol NaOH

In base on the reaction, it’s needed 1 mol of NaOH to neutralize 1 mole of HBr, so to neutralize 0.0625 moles of HBr its needed 0.0625 mol of NaOH:

0.0625 mol HBr – 0.03125 mol HBr = 0.03125 mol HBr

These are the moles free in the solution, and we going to use them to calculate the pH:

pH = -log [ H]

pH = - log [ 0.03125 ] = 1.5

c) Calculate the pH after adding 500 mL of 0.125M NaOH

NaOH:

mol = [M] × L

mol = 0.125 M × 0.500L

mol = 0.0625 mol NaOH

In base on the reaction, it’s needed 1 mol of NaOH to neutralize 1 mole of HBr, so to neutralize 0.0625 moles of HBr its needed 0.0625 mol of NaOH:

0.0625 mol HBr – 0.0625 mol HBr = 0 HBr

pH = 7

d) Calculate the pH after adding 600 mL of 0.125M NaOH.

NaOH:

mol = [M] × L

mol = 0.125 M × 0.600L

mol = 0.075 mol NaOH

In base on the reaction, it’s needed 1 mol of NaOH to neutralize 1 mole of HBr, so to neutralize 0.0625 moles of HBr its needed 0.0625 mol of NaOH:

0.075 mol NaOH – 0.0625 mol NaOH = 00125 NaOH

These are the moles free in the solution, and we going to use them to calculate the pH:

pOH = -log [ OH]

pOH = - log [ 0.0125 ] = 1.90

pH + pOH = 14

pH = 14- pOH = 14 – 1.90 = 12.1

4 0

3 years ago

What is the theoretical yield of ammonia that can be obtained from the reaction of 10.0 g of H2 and excess N2?

zubka84 [21]

Theoretical yield is the ideal number, so we'll assume it all reacted without issue.
$\frac{10.0gH _{2} }{1}$ × $\frac{1molH_{2} }{2.016gH _{2} }$ × $\frac{2molNH _{3} }{3molH _{2} }$ × $\frac{17.03gNH _{3} }{1molNH _{3} }$ =56.3gNH↓3

8 0

3 years ago

Read 2 more answers

Part B Identify the sets of quantum numbers that describe all the electrons in the ground state of a neutral beryllium atom, Be.

dmitriy555 [2]

Answer: The set of quantum numbers for the electrons in Be atom are (2, 1, -1, 1/2), (1, 0, 0, 1/2), (1, 0, 0, -1/2) and (2, 0, 0, -1/2)

Explanation:

There are 4 quantum numbers:

Principal Quantum number (n) specifies the energy of the electron in a shell.
Azimuthal Quantum number (l) specifies the shape of an orbital. The value of it lies in the range of 0 to (n-1)
Magnetic Quantum number (m) specifies the orientation of the orbital in space. The value of it lies in the range of -l to +l
Spin Quantum number (s) specifies the spin of an electron in an orbital. It can either have a value of $+\frac{1}{2}$ or $-\frac{1}{2}$