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Oksanka [162]
3 years ago
7

How many moles of oxygen (O) atoms are in a sample of 3.98 × 1023 atoms? 0.661 mol O 1.51 mol O 6.60 × 1022 mol O 2.40 × 1047 mo

l O
Chemistry
1 answer:
lidiya [134]3 years ago
7 0
To find moles from any number of atoms, always divide by the constant called Avogadro's Number. This number is representative of the number of atoms or molecules in a mole of any substance and is equal to about 6.022* 10^{23} 
.

So, for this problem, we take the number of atoms of oxygen and divide by Avogadro's Number. 

\frac{3.98*  10^{23}  O_{2} atoms  }{6.022*  10^{23} atoms/mol  } = 0.6609 moles

Answer: 0.661 moles (after rounding)

Make sense?
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Arrange the metals used in this experiment (including H2 and Ag) in order of decreasing reactivity (most reactive metal first).
jarptica [38.1K]

Answer:

Na, Ca, Mg, All, Zn, Fe, Sn, Pb, H2, Cu, Ag

Explanation:

This is how metals are arranged in the electrochemical series.

Use the following to remember the order:

King Nathan Can Manage All Zone Freely Since Probably He Can Handle All Ages

Each word represent the order

K, Na, Ca, Mg, All, Zn, Fe, Sn, Pb, H2, Cu, Hg, Ag, Au

6 0
4 years ago
For salt formation procedure crude lidocaine should be dissolved in diethyl ether and 2 ml of 2.2 M sulfuric acid should be adde
mixas84 [53]

Answer:

20 equivalents of sulfuric acid are needed to per equivalent of lidocaine.

Explanation:

To do this calculation we should take in account the key information given:

<em>2 mL (0.02 L) of sulfuric acid (H2SO4) 2.2 M per 1 g of lidocaine (molecular weight=234.34 g/mol)</em>

So we can calculate from here the number of moles of each compound needed for the procedure.

Starting with the sulfuric acid, we know that the molar concentration is defined as [concentration] =n(moles number)/V(volume).

So n=[concentration]*V, and therefore :

n(H2SO4)=2.2 M * 0.02 L=0.044 mol

While the moles of lidocaine can be calculated as n(moles number)=m(mass amount)/mW(molecular weight), so:

n(lidocaine)=m(lidocaine)/mW(lidocaine)= 1 g /234,34 g/mol~0,0043 mol.

Now we can calculate the equivalents.

Take in account that for sulfuric acid, de number of equivalents per mole is 2 (because of the double dissociation of the acid), while the number of equivalents per mole of lidocaine is 1.

Then we can conclude that:

0,0043 equivalents of lidocaine need 0,088 equivalents of sulfuric acid

1 equivalent of lidocaine need (0,088/0.0043)=20,46~20 equivalents of sulfuric acid

Finally, we can conclude that for the described procedure, 20 equivalents of sulfuric acid per equivalent of lidocaine are needed.

4 0
3 years ago
Select the correct structure that
Leni [432]

Answer:

Explanation:

its b

8 0
3 years ago
I need help on thiss
Sergio039 [100]

The reaction is not balanced

<h3>Further explanation</h3>

Given

Reaction

2Fe(s)+3O₂(g)⇒2Fe₂O₃(s)

Required

The number of atoms

Solution

In a balanced chemical equation, the number of atoms in the compound that reacts (the reactants and products) will have the same number

Reactants : Fe(s)+O₂(g)

Fe = 2 atoms

O = 3 x 2 = 6 atoms

Products : Fe₂O₃(s)

Fe = 2 x 2 = 4 atoms

O = 2 x 3 = 6 atoms

The reaction is not balanced because the number of Fe atoms is not the same

The balanced reaction should be:

4Fe(s)+3O₂(g)⇒2Fe₂O₃(s)

8 0
3 years ago
3.5g of a Certain compound X, known to be made of carbon, hydrogen, and perhaps oxygen, and to have a molecular molar mass of 15
shutvik [7]

Answer:

C₅H₁₀O₅

Explanation:

1. Calculate the mass of each element in 2.78 mg of X.

(a) Mass of C

\text{Mass of C} = \text{5.13 g CO}_{2}\times \dfrac{\text{12.01 g C}}{\text{44.01 g }\text{CO}_{2}}= \text{1.400 g C}

(b) Mass of H

\text{Mass of H} = \text{2.10 g H$_{2}$O}\times \dfrac{\text{2.016 g H}}{\text{18.02 g H$_{2}$O}} = \text{0.2349 g H}

(c) Mass of O

Mass of O = 3.5 - 1.400 - 0.2349 = 1.87 g

2. Calculate the moles of each element

\text{Moles of C = 1400  mg C}\times\dfrac{\text{1 mmol C}}{\text{12.01 mg C }} = \text{116.6 mmol C}\\\\\text{Moles of H = 234.9 mg H} \times \dfrac{\text{1 mmol H}}{\text{1.008 mg H}} = \text{233.1 mmol H}\\\\\text{Moles of O = 1870 mg O} \times \dfrac{\text{1 mmol O}}{\text{16.00 mg O}} = \text{116 mmol O}

3. Calculate the molar ratios

Divide all moles by the smallest number of moles.

\text{C: } \dfrac{116.6}{116.6}= 1\\\\\text{H: } \dfrac{233.1}{116.6} = 1.999\\\\\text{O: } \dfrac{116}{116.6} = 1.00

4. Round the ratios to the nearest integer

C:H:O = 1:2:1

5. Write the empirical formula

The empirical formula is CH₂O.

6. Calculate the molecular formula.

EF Mass = (12.01 + 2.016  + 16.00) u  = 30.03 u

The molecular formula is an integral multiple of the empirical formula.

MF = (EF)ₙ

n = \dfrac{\text{MF Mass}}{\text{EF Mass }} = \dfrac{\text{150 u}}{\text{30.03 u}} = 5.00  \approx 5

MF = (CH₂O)₅ = C₅H₁₀O₅

The molecular formula of X is C₅H₁₀O₅.

8 0
4 years ago
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