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3 years ago

You start with 12.94 g sample of a mixture containing SiO2, NaCl, and NH4Cl. If after subliming

Chemistry

1 answer:

Tema [17]3 years ago

8 0

<h3>Answer:</h3>

83.23 %

<h3>Explanation:</h3>

<u>We are given;</u>

Mass of the sample mixture is 12.94 g
Mass of the remaining mixture after sublimation is 2.17 g

We are required to get the mass percent of NH₄Cl in the original sample

<h3>Step 1 : Calculate mass of NH₄Cl in the original sample;</h3>

Mass of NH₄Cl = Total mass of the mixture - remaining mass after sublimation

= 12.94 g - 2.17 g

= 10.77 g

<h3>Step 2: Percent by mass of NH₄Cl in the original sample</h3>

% of NH₄Cl by mass =(Mass of NH₄Cl÷Total mass of original sample)×100

= (10.77 g ÷ 12.94 g) × 100

= 83.23 %

Therefore, the percent by mass of NH₄Cl in the original sample is 83.23%

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How does a concave lens differ from a convex lens? A) A convex lens is another way to describe a plane mirror; a concave lens is

elixir [45]

<h3><u>Answer;</u></h3>

C) A convex lens has a thick center and thin edges; a concave lens has a thin center and thicker edges.

<h3><u>Explanation;</u></h3>

Convex lens refers to the lens which merges the light rays at a particular point, that travels through it, while a concave lens can be identified as the lens which disperses the light rays around, that hits the lenses.
A convex lens is thicker at the center, as compared to its edges, while a concave lens is thinner at the center as compared to its edges.
A concave lens is thicker at the edges than in the middle and spreads light rays apart producing an image smaller than the actual object. A convex lens on the other hand, is thinner at the edges and thicker towards the center, that is they are bent towards a central point.

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3 years ago

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How many moles of hydrogen are in 5.2 moles of c7h18

alexandr1967 [171]

The percentage of hydrogen in C7H18 is calculated as follows:
[18/(12*7+1*8)]*100=18%
The amount of hydrogen in 5.2moles is given by:(18/100)*5.2=0.94moles

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3 years ago

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How many moles are in 50 g of CO2

murzikaleks [220]

Answer:

1.1 mol

Explanation:

n=m/M, where n is moles, m is mass, and M is molar mass.

M of CO2 = 12.01+16.00+16.00 = 44.01g/mol

n=50g/44.01g/mol

n = 1.13610543 mol

n ≈ 1.1 mol

Hope that helps

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2 years ago

Complete and balance the following redox equation using the set of smallest whole– number coefficients. Now sum the coefficients

Elena L [17]

Answer : The balanced chemical equation in a acidic solution is,

$BrO_3^-(aq)+6H^+(aq)+3Sb^{3+}(aq)\rightarrow Br^-(aq)+3H_2O(l)+3Sb^{5+}(aq)$

The sum of the coefficients is, 17

Explanation :

Redox reaction or Oxidation-reduction reaction : It is defined as the reaction in which the oxidation and reduction reaction takes place simultaneously.

Oxidation reaction : It is defined as the reaction in which a substance looses its electrons. In this, oxidation state of an element increases. Or we can say that in oxidation, the loss of electrons takes place.

Reduction reaction : It is defined as the reaction in which a substance gains electrons. In this, oxidation state of an element decreases. Or we can say that in reduction, the gain of electrons takes place.

Rules for the balanced chemical equation in acidic solution are :

First we have to write into the two half-reactions.

Now balance the main atoms in the reaction.

Now balance the hydrogen and oxygen atoms on both the sides of the reaction.

If the oxygen atoms are not balanced on both the sides then adding water molecules at that side where the less number of oxygen are present.

If the hydrogen atoms are not balanced on both the sides then adding hydrogen ion $(H^+)$ at that side where the less number of hydrogen are present.

Now balance the charge.

The given chemical reaction is,

$BrO_3^-(aq)+Sb^{3+}(aq)\rightarrow Br^-(aq)+Sb^{5+}(aq)$

The oxidation-reduction half reaction will be :

Oxidation : $Sb^{3+}\rightarrow Sb^{5+}$

Reduction : $BrO_3^-\rightarrow Br^-$

First balance the main element in the reaction.

Oxidation : $Sb^{3+}\rightarrow Sb^{5+}$

Reduction : $BrO_3^-\rightarrow Br^-$

Now balance oxygen atom on both side.

Oxidation : $Sb^{3+}\rightarrow Sb^{5+}$

Reduction : $BrO_3^-\rightarrow Br^-+3H_2O$

Now balance hydrogen atom on both side.

Oxidation : $Sb^{3+}\rightarrow Sb^{5+}$

Reduction : $BrO_3^-+6H^+\rightarrow Br^-+3H_2O$

Now balance the charge.

Oxidation : $Sb^{3+}\rightarrow Sb^{5+}+2e^-$

Reduction : $BrO_3^-+6H^++6e^-\rightarrow Br^-+3H_2O$

The charges are not balanced. Now multiplying oxidation reaction by 3 and then adding both equation, we get the balanced redox reaction.

Oxidation : $3Sb^{3+}\rightarrow 3Sb^{5+}+6e^-$

Reduction : $BrO_3^-+6H^++6e^-\rightarrow Br^-+3H_2O$

The balanced chemical equation in acidic medium will be,

$BrO_3^-(aq)+6H^+(aq)+3Sb^{3+}(aq)\rightarrow Br^-(aq)+3H_2O(l)+3Sb^{5+}(aq)$

The sum of the coefficients = 1 + 6 + 3 + 1 + 3 + 3

The sum of the coefficients = 17

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3 years ago

Is a molecule positive or negative?

elixir [45]

It can be either they can have a negative or positive charge more specifically negatively charged molecule would called an anion and a positive one would be cation.

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3 years ago