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3 years ago

12

Use the periodic table to calculate the molar mass of each of the following compounds. Give your answer to the correct number of

significant figures.
Iron(III) oxide (Fe2O3): g/mol

1 answer:

Anna [14]3 years ago

7 0

Fe: 2 x 55.845 = 111.69
O: 3 x 15.9994= 47.9982

111.69 + 47.9982 = 159.69 g/mol

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A bag of gumdrops contains 17 orange gumdrops, 10 yellow gumdrops, and 17 black gumdrops.

Leviafan [203]

What is the question?

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3 years ago

How many moles are in 7.2x10^15 atoms of Pb?

fiasKO [112]

<h3>Answer:</h3>

1.2 × 10⁻⁸ mol Pb

<h3>General Formulas and Concepts:</h3>

<u>Math</u>

<u>Pre-Algebra</u>

Order of Operations: BPEMDAS

Brackets
Parenthesis
Exponents
Multiplication
Division
Addition
Subtraction

Left to Right<u> </u>

<u>Chemistry</u>

<u>Atomic Structure</u>

Avogadro's Number - 6.022 × 10²³ atoms, molecules, formula units, etc.

<u>Stoichiometry</u>

Using Dimensional Analysis

<h3>Explanation:</h3>

<u>Step 1: Define</u>

[Given] 7.2 × 10¹⁵ atoms Pb

<u>Step 2: Identify Conversions</u>

Avogadro's Number

<u>Step 3: Convert</u>

[DA] Set up: $\displaystyle 7.2 \cdot 10^{15} \ atoms \ Pb(\frac{1 \ mol \ Pb}{6.022 \cdot 10^{23} \ atoms \ Pb})$
[DA] Multiply/Divide [Cancel out units]: $\displaystyle 1.19562 \cdot 10^{-8} \ mol \ Pb$

<u>Step 4: Check</u>

<em>Follow sig fig rules and round. We are given 2 sig figs.</em>

1.19562 × 10⁻⁸ mol Pb ≈ 1.2 × 10⁻⁸ mol Pb

6 0

3 years ago

What is the total number of moles represented by 20 grams of CACO3

Nutka1998 [239]

Answer:

B. 0.2.

Explanation:

We can use the relation:

<em>n = mass/molar mass</em>

mass of CaCO₃ = 20 g, molar mass of CaCO₃ = 100.0869 g/mol.

<em>∴ n = mass/molar mass = </em>(20 g)/(100.0869 g/mol) <em>= 0.1998 ≅ 0.2 mol.</em>

<em></em>

<em>So, the right choice is: B. 0.2.</em>

8 0

3 years ago

Magnesium hydroxide is added to a solution of hydrochloric acid. A reaction occurs and magnesium chloride and water are formed.

kodGreya [7K]

Answer:Magnesium (Mg) is a - reactant

Hydrogen (H2) is a - product

magnesium chloride (MgCI2) is a - product

hydrochloric acid (HCI) is a - reactant

Explanation: It’s in my notes

8 0

3 years ago

At a certain temperature, the solubility of strontium arsenate, sr3(aso4)2, is 0.0560 g/l. what is the ksp of this salt at this

REY [17]

The solution for this problem is:
Get into moles first. .0560 grams over 540.8 grams per mole = 1.04 x l0^-4 moles
Sr3(As04)2 = 3 Sr++(aq) plus 2 As04^-3(aq)
Ksp = (Sr++)^3(As04^-3)^2
(Sr++) = 3 X 1.04 x l0^-4= 3.11 x l0^-4
(As04^-3) = 2 x 1.04 x l0^-4= 2.07 x l0^-4
Ksp = (1.04 x l0^-4)^3 (2.07 x l0^-4)^2 which equals 4.82 x 10^-20

5 0

3 years ago