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4 years ago

Balancing chemical equations

Chemistry

1 answer:

mojhsa [17]4 years ago

4 0

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Which statement describes a property that is unique to metalloids?

hodyreva [135]

Answer:

Metalloids are semiconductive.

Explanation:

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3 years ago

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What mass in grams would 5.7L of hydrogen gas occupy at STP?

tekilochka [14]

Answer: The correct answer is: " 0.54 g " .

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Explanation:

Note that "hydrogen gas" is:

H₂ (g) ; that is: a "diatomic element" (diatomic gas) ;

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The molecular weight of "H" is: 1.00794 g ;

(From the Periodic Table of Elements).

So, the molecular weight of: H₂ (g) is:

" 1.00794 g * 2 = 2.01588 g ; {use calculator) ;

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Note the conversion for a gas at STP:

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1 mol of a gas = 22.4 L gas;

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i.e. " 1 mol / 22.4 L " ;

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So: " 5.7 L H₂ (g) $* \frac{1 mol H_{2} }{22.4 L} *\frac{2.01588 g}{mol} =? ;$

The "L" ("literes" cancel out to "1" ; since "L/L = 1 ;

The "mol" (moles) cancel out to "1" ; since "mol/mol = 1 ;

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and we are left with:

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[5.7 * 2.104588 g ] / 22.4 = ? g ;

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→ [ 11.9961516 g ] / 22.4 =

0.53554248214 g ;l

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We round this value to: " 0.54 g " ;

→ since "5.7 L " has 2 (two) significant figures;

22.4 is an exact number conversion;

and "5.7 L" has fewer significant figures than:

" 2.104588 " ; or: " 1.00794 " .

→ as such: We round to "2 (two) significant figures."

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Hope this is helpful. Wishing you the best in your academic endeavors!

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3 years ago

Primary needs in South Africa and secondary needs and wants in South Africa<br>

leonid [27]

Answer:

Food, safe water, housing, education, and health care are examples of basic needs. Wants are desires that can be satisfied by goods and services.Secondary needs are the desires and wants that become important when primary needs are satisfied. Definition (2): Secondary needs are connected with the desire for satisfaction and pleasure of the human being: designer articles or furniture, the high-tech and the newest cell phone, jewelry, a luxury car, etc.

お役に立てば幸いです

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2 years ago

Calculate the molality of a solution prepared by dissolving 175 g of KNO3 in 750 g of water. (round to nearest hundreth)

Wittaler [7]

We will get the molality from this formula:
Molality = no.of moles of solute / Kg of solvent

So first we need the no.of moles of KNO3 = the mass of KNO3 / molar mass of KNO3
no.of moles of KNO3 = 175 / 101.01 = 1.73 mol
By substitution in the molality formula:
∴ molality = 1.73 / (750/1000) = 2.3 Molal

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3 years ago

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Element X has two isotopes. If 72.0% of the element has an isotope mass of 84.9 atomic mass units, and 28.0% of the element has

bija089 [108]

<h2>Answer:</h2>

Average atomic mass of an element is the sum of the masses of its isotopes each multiplied by its natural abundance

$\footnotesize \longrightarrow \: \rm Average \: atomic \: mass = \dfrac{ \sum\limits \: \% age \: of \: each \: isotope \times Atomic \: mass }{100} \\$

$\footnotesize \longrightarrow \: \rm Average \: atomic \: mass = \dfrac{ 72 \times84.9 + 28 \times 87 }{100} \\$

$\footnotesize \longrightarrow \: \rm Average \: atomic \: mass = \dfrac{ 6112.8 + 2436 }{100} \\$

$\footnotesize \longrightarrow \: \rm Average \: atomic \: mass = \dfrac{ 8548.8 }{100} \\$

$\footnotesize \longrightarrow \: \bf Average \: atomic \: mass = 85.488 \: amu \\$

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2 years ago