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3 years ago

You weigh a 24K gold chain and find that it weighs 400 grams. Determine home many moles of gold atoms you have

Chemistry

1 answer:

makkiz [27]3 years ago

4 0

Answer:

2.03 moles of Gold

Explanation:

Gold is one of the most precious metal metal used in many applications and mainly as a jewellery. In terms of purity it is categorized in Karats. 24 Karat is considered the purest Gold (i.e. 100 % Gold) while other Karats (14, 18, 22 e.t.c) are alloys with other metals and gyms.

Data Given:

Mass of Gold = 400 g

A.Mass of Gold = 196.97 g.mol⁻¹

Calculate Moles of Gold as,

Moles = Mass ÷ M.Mass

Putting values,

Moles = 400 g ÷ 196.97 g.mol⁻¹

Moles = 2.03 moles of Gold

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How many molecules of CH4 are in 48.2 g of this compound? A) 2.00 x 1023 B) 5.00 x 10-24 C)1.81 x 1024 D) 4.00 E) 4.64 x 1026 10

Tasya [4]

Answer: The correct answer is Option C.

Explanation:

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$

Given mass of methane = 48.2 g

Molar mass of methane = 16 g/mol

Putting values in above equation, we get:

$\text{Moles of }CH_4=\frac{48.2g}{16g/mol}=3.0125mol$

According to mole concept:

1 mole of compound contains $6.022\times 10^{23}$ number of molecules.

So, 3.0125 moles of methane will contain = $3.0125\times 6.022\times 10^{23}18.141\times 10^{23}=1.81\times 10^{24}$ number of molecules.

Hence, the correct answer is Option C.

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3 years ago

Terry heats two different masses of substance A to different temperatures, and measures the amounts of both carbon dioxide and w

Naddika [18.5K]

Answer:

This experiment is uncontrolled because two different masses of substance A are used.

Explanation:

A controlled experiment is a structured experiment aimed at testing a particular observation or observations. The setup of a controlled experiment helps to determine the reason why a particular observation occurs and what must have led to it.

In the experiment highlighted above, different masses of a substance were used, they were heated to different temperatures. The set up does not show any correlation between the masses of substances heated and the temperatures. It is even difficult to try to predict the hypothesis for this kind of experimental set up. All the variables in play can best be assumed to be independent of one another.

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3 years ago

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chubhunter [2.5K]

Answer: i believe it’s the second one !

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3 years ago

Complete the sentence. The atomic number of an element is found by counting the number of _______ in an atom. A. isotopes B. ele

Kipish [7]

D.) Protons............

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Draw the Lewis structures for CH3OH, CH2O and HCOOH. Indicate the hybrid orbital used in the sigma bonds for each of the carbon

sdas [7]

Answer:

See figure 1

Explanation:

For this question, we have to remember that in the lewis structures all atoms must have 8 electrons. And each atom would have a different value of valence electrons:

Carbon => 4

Oxygen=> 6

Hydrogen=> 1

Additionally, for the hybridizations we have to remember that:

$Sp^3$ => 4 single bonds

$Sp^2$ => 1 double bond

$Sp^1$ => 1 double bond

With this in mind, the formaldehyde and formic acid would have $Sp^2$ carbons and the ethanol an $Sp^3$ carbon.

Finally, for the oxidation state. We have to remember that if we have more bonds with oxygen, we will have more oxidation. Therefore, the carbon that has more oxidation is the one in the formic acid (we have several bonds with oxygen).

See figure 1

I hope it helps!

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3 years ago