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Dmitrij [34]
4 years ago
5

The insulating and packing material Styrofoam is a dating and packing material Styrofoam is a polymer of styrene. Find the molec

ular formula of sy ene given its percent composition: 922 775 H The approximate molar mass of styrene is 104 g/mol. A) CHE BỊ CH C)C12H D) CH12 E) C8Hg
Chemistry
1 answer:
Nataly [62]4 years ago
8 0

Explanation:

In order to find the molecular formula, we have to find the empirical formula first of all.

It is known that is a styrofoam, elements present are carbon and hydrogen atoms.

Element     %         Atomic mass       Molar ratio           Simple ratio

    C        92.25          12.01              \frac{92.25}{12.01} = 7.68                 \frac{7.68}{7.68} = 1

     H        7.75            1.008            \frac{7.75}{1.008} = 7.68                 \frac{7.68}{7.68} = 1

As empirical formula of styrofoam is C_{x}H_{x}.

Hence, empirical mass = (12.01 + 1.008) g/mol = 13.018 g/mol = 13.0 g/mol (approx)

Molar mass given is 104 g/mol.

So,     \frac{\text{molar mass}}{\text{empirical formula mass}} = \frac{104}{13.0} = 8

Thus, we can conclude that molecular formula of the given styrene is C_{8}H_{8}.

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a chemist measures 20.00 moles of water H2O . How many grams of water is that? PLS HELP WILL GIVE BRAINLIST
DedPeter [7]

Answer:

360.4 grams

Explanation:

The first step is to find the molecular mass of H2O. The molecular mass of a molecule is the atomic masses added altogether. Because there are 2 hydrogens, we need 2x the atomic mass. 2(1.01) + 1(16.00) = 18.02 amu.

The molar mass of H2O is 18.02 g/mol. This is the unit converter to change from moles to grams

20.00 mol H2O *\frac{18.02 g H2O}{1 mol H2O} =360.4 g

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4 years ago
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3 years ago
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A chemical equation is balanced when the
Arada [10]

a balanced chemical equation occurs when the number of the atoms involved in the reactants side is equal to the number of atoms in the products side.

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Consider the heating curve for water. A graph of the heating curve for water has time in minutes on the horizontal axis and Temp
Zolol [24]

Answer:

0°C.

Explanation:

Hello,

In this case, given the heating curve of water on the attached document, we can notice that at 0 °C the solid starts melting, which means that the melting point is reached. Melting point is known as a physical change whereby a solid changes to liquid by the addition of heat as it allows the molecules to separate to each other.

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4 0
3 years ago
Complete and balance the following equation: S(s)+HNO3(aq)→H2SO3(aq)+N2O(g)(acidic solution)
meriva

Answer:- The balanced equation is, 2HNO_3(aq)+2S(s)+H_2O(l)\rightarrow N_2O(g)+2H_2SO_3(aq) .

Solution:- Oxidation number of S is increasing from 0 to 4 and so it is oxidation. Oxidation number of N is decreasing from 5 to 1 and so it is reduction.

We write the oxidation and reduction half equations and balance them. The given reaction is taking place in an acidic medium.

First of all we balance all the atoms other than H and O. Then oxygen is balanced by adding H_2O and hydrogen is balanced by adding H^+ . Charge is balanced by adding electrons.

To makes the electrons equal for both the half equations we multiply the equation/equations by appropriate numbers.

Oxidation half equation:

S(s)\rightarrow H_2SO_3(aq)

S is already balanced. To balance O, we need to add three water molecules to the left side:

S(s)+3H_2O(l)\rightarrow H_2SO_3(aq)

For balancing hydrogen, we need to add 4 hydrogen ions to the right side:

S(s)+3H_2O(l)\rightarrow H_2SO_3(aq)+4H^+(aq)

Now to balance the charge we need to add 4 electrons to the right side:

S(s)+3H_2O(l)\rightarrow H_2SO_3(aq)+4H^+(aq)+4e^-

Reduction half equation:

HNO_3(aq)\rightarrow N_2O(g)

To balance N, we need to multiply left side by 2:

2HNO_3(aq)\rightarrow N_2O(g)

For balancing oxygen, we need to add 5 water molecules to the right side:

2HNO_3(aq)\rightarrow N_2O(g)+5H_2O(l)

To balance hydrogen, we need to add 8 hydrogen ions to the left side:

2HNO_3(aq)+8H^+(aq)\rightarrow N_2O(g)+5H_2O(l)

Now, for charge balance, we need to add 8 electrons to the left side:

2HNO_3(aq)+8H^+(aq)+8e^-\rightarrow N_2O(g)+5H_2O(l)

First half equation has 4 electrons and second half equation has 8 electrons.

To make the electrons equal, we need to multiply oxidation half equation by 2:

2S(s)+6H_2O(l)\rightarrow 2H_2SO_3(aq)+8H^+(aq)+8e^-

Now we add both of these two half equations and cancel out common species. What we get on doing this is:

2HNO_3(aq)+2S(s)+H_2O(l)\rightarrow N_2O(g)+2H_2SO_3(aq)



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3 years ago
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