How many mol molecule oxygen are 3 mol oxygen atoms

In the formula 5CaSO4 the total number of sulfur atoms present is a. 1. b. 5. c. 9. d. 20?

podryga [215]

The answer is b . (1*5=5)

4 0

3 years ago

A chemist mixes 1.00 g CuCl2 with an excess of (NH4)2HPO4 in dilute aqueous solution . He measures the evolution of 670 J of hea

kaheart [24]

Answer:

$\Delta H$ will be 90054 J

Explanation:

Number of moles = (mass)/(molar mass)

Molar mass of $CuCl_{2}$ = 134.45 g/mol

So, 1.00 g of $CuCl_{2}$ = $\frac{1.00}{134.45}mol$ of $CuCl_{2}$ = 0.00744 mol of $CuCl_{2}$

0.00744 mol of $CuCl_{2}$ produces 670 J of heat

So, 1 mol of $CuCl_{2}$ produces $\frac{670}{0.00744}J$ of heat or 90054 J of heat

4 0

3 years ago

What is the molarity of a solution in which 55. 49 g of calcium chloride is dissolved in enough water to make 500. ml of solutio

PSYCHO15rus [73]

The molarity of a solution in which 55. 49 g of calcium chloride is dissolved in enough water to make 500. ml of solution is 1M.

<h3>What is molarity? </h3>

It is defined as number of moles of solute divided by volume of solution.

Given,

Mass of CaCl2 =55.49g

Molar mass of CaCl2 =40+35+35=110g

Mole= given mass/ molar mass

= 55.49/110=0.50mol.

Now, putting all values we get the molarity

Molarity =0.5×1000/500=1M

Thus, the molarity of given solution is 1M.

learn more about Molarity:

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4 0

1 year ago

How many moles are in a 12.0 g sample of NiC12

Nady [450]

Answer:

0.17 moles

Explanation:

In the elements of the periodic table, the atomic mass = molar mass. <u>Ex:</u> Atomic mass of Carbon is 12.01 amu which means molar mass of Carbon is also 12.01g/mol.

In order to find the # of moles in a 12 g sample of NiC-12, we will need to multiply the number of each atom by its molar mass and then add the masses of both Nickel and C-12 found in the periodic table:

Molar Mass of Ni (Nickel): 58.69 g/mol

Molar Mass of C (Carbon): 12.01 g/mol

Since there's just one atom of both Carbon and Nickel, we just add up the masses to find the molar mass of the whole compound of NiC-12.

58.69 g/mol of Nickel + 12.01 g/mol of Carbon = 70.7 g/mol of NiC-12

There's 12g of NiC-12, which is less than the molar mass of NiC-12, so the number of moles should be less than 1. In order to find the # of moles in NiC-12, we need to do some dimensional analysis:

12g NiC-12 (1 mol of NiC-12/70.7g NiC-12) = 0.17 mol of NiC-12
The grams cancel, leaving us with moles of NiC-12, so the answer is 0.17 moles of NiC-12 in a 12 g sample.

<em>P.S. C-12 or C12 just means that the Carbon atom has an atomic mass of 12amu and a molar mass of 12g/mol, or just regular carbon.</em>

5 0

3 years ago

Calculate the concentrations of all species present in a 0.26 M solution of ethylammonium chloride (C2H5NH3Cl).

Alina [70]

Answer:

0.00000223

Explanation:

pKa for C2H5NH3+ = 10.7

pKw = 14.0

pKa + pKb = pKw

10.7 + pKb = 14.0

pKb = 14.0 - 10.7

pKb = 3.30

C2H5NH3Cl is a salt of ethylamine and HCl so it will dissolve in water to produce C2H5NH3^+ + Cl^-

The base hydrolysis reaction: C2H5NH3^+(aq) + H2O(l) <=> C2H5NH2(aq) + H3O^+(aq)

This reaction is described by Kb.

Kb = [C2H5NH2][H3O^+]/[C2H5NH3^+]

Let [C2H5NH2] = [H3O^+] = x,

so [C2H5NH3^+] = 0.26 - x

Kb = x^2/(0.26 - x) = 2.00 x 10^-11

Let's solve for x. In this equation, It is possible to solve without the use quadratic equation. So we can assume that 0.26 - x is approximately equal to 0.26. We won't know until we do the calculation.

We get: x^2 + 2.00 x 10^-11x - 4.99 x 10^-12 = 0

With the use of a quadratic calculator.

x = 2.23 x 10^-6 M = [C2H5NH2] = [H3O^+]

0.26 - x is just 0.26 M in this problem because 2.23 x 10^-6 M is insignificant.

[C2H5NH3^+] = 0.26 M = [Cl^-]

NOTE:

pH = -log [H3O^+] = -log(2.23 x 10^-6) = 5.65

Ka is the acid dissociation constant

Kb is the base dissociation constant

5 0

3 years ago