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3 years ago

Plz help thx...

Chemistry

2 answers:

Damm [24]3 years ago

7 0

1) For example, sodium oxide (Na₂O).

One one molecule of sodium oxide has one sodium atome (Na) and two oxygen atoms (O).

The subscript after element shows the number of elements in a molecule.

2) Yes, it possible for two different compounds to be made from the exact same two elements.

This are isomers, same molecular formula, but different arrangements of atoms.

For example, n-butane (C₄H₁₀) and 2-methylpropane (C₄H₁₀).

3) There are large number of compounds in this world, around 40 millions.

ArbitrLikvidat [17]3 years ago

4 0

Answer:

salt

Explanation:

sodium chloride. 1 sodium atom and one hydrogen atom.

It is possible because there could be more atoms, making it more or less reactant.

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Bingel [31]

Answer:

Solution A is 1,000 times more acidic than Sol. B

Explanation:

for pH values we use scientific notation:

-log10 c (where c is the hydrogen ion concentration) is used to notate pH value (think of it as a unit)

ie:

10^-2 is sol A 10^-5 is sol B

5-2 is 3

10^-3 = 1000

there's a diff of 1,000 between the solutions.

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3 years ago

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jeka57 [31]

Answer:

They are similarly charged, which is why they repel each other.

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2 years ago

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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.

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<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: $\displaystyle 7.2 \cdot 10^{15} \ atoms \ Pb(\frac{1 \ mol \ Pb}{6.022 \cdot 10^{23} \ atoms \ Pb})$
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1.19562 × 10⁻⁸ mol Pb ≈ 1.2 × 10⁻⁸ mol Pb

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3 years ago

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3 years ago

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Calculate the standard reaction enthalpy for the reaction NO2(g) → NO(g) + O(g) given +142.7 kJ/mol for the standard enthalpy of

bulgar [2K]

Answer:

The standard reaction enthalpy for the given reaction is 235.15 kJ/mol.

Explanation:

$O_2(g) \rightarrow \frac{2}{3}O_3(g),\Delta H^o_{1}=142.7 kJ/mol$ ..[1]

$O_2(g) \rightarrow 2 O(g),\Delta H^o_{2}=498.4 kJ/mol$ ..[2]

$NO(g) + O_3(g)\rightarrow NO_2(g) + O_2(g) ,\Delta H^o_{3} = -200 kJ/mol$ ..[3]

$NO_2(g)\rightarrow NO(g) + O(g),\Delta H^o_{4}=?$ ..[4]

Using Hess's law:

Hess’s law of constant heat summation states that the amount of heat absorbed or evolved in a given chemical equation remains the same whether the process occurs in one step or several steps.

2 × [4] = [2]- (3 ) × [1] - (2) × [3]

$2\times \Delta H^o_{4}=\Delta H^o_{2} -3\times \Delta H^o_{1}-2\times \Delta H^o_{3}$

$2\times \Delta H^o_{4}=498.4 kJ/mol-3\times 142.7 kJ/mol-2\times -200 kJ/mol$

$2\times \Delta H^o_{4}=470.3 kJ/mol$

$\Delta H^o_{4}=\frac{470.3 kJ/mol}{2}=235.15 kJ/mol$

The standard reaction enthalpy for the given reaction is 235.15 kJ/mol.

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3 years ago