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3 years ago

9

Which balanced equation represents a chemical change? A) H2O() + energy → H2O(g) B) 2H2O() + energy → 2H2(g) + O2(g) C) H2O() →

H2O(s) + energy D) H2O(g) → H2O() + energy

1 answer:

IgorC [24]3 years ago

5 0

Although your question is incomplete, I believe 'B' is the answer, as the Oxygen separates from the Hydrogen

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Determine the mass of carbon iv oxide ,produced on burning 104g of ethyne

mars1129 [50]

163 grams (3 sig. fig.).

<h3>Explanation</h3>

Formula of <em>carbon(IV) oxide</em> (a.k.a. carbon dioxide): $\text{CO}_2$ .
Molar mass of $\text{CO}_2$ : $\underbrace{12.01}_{\text{C}} + 2\times\underbrace{16.00}_{\text{O}}=44.01\;\text{g}\cdot\text{mol}^{-1}$ .

Formula of ethyne: structural $\text{H}-\text{C}\equiv\text{C}-\text{H}$ or molecular $\text{C}_2\text{H}_2$ .
Molar mass of $\text{C}_2\text{H}_2$ : $2\times\underbrace{12.01}_{\text{C}}+2 \times\underbrace{16.00}_{\text{O}} = 56.02\;\text{g}\cdot\text{mol}^{-1}$ .

All carbon atoms in that 104 grams of ethyne will end up in $\text{CO}_2$ . Number of moles of molecules in 104 grams of ethyne:

$n = \dfrac{m}{M} = \dfrac{104}{56.02} = 1.85648\;\text{mol}$ .

There are two carbon atoms in each ethyne molecule. Number of carbon atoms in that many ethyne molecules:

$n(\text{C}) = 2\;n(\text{C}_2\text{H}_2) = 3.71296\;\text{mol}$ .

There are one carbon atom in each $\text{CO}_2$ molecule. In case oxygen is in excess, all those carbon atoms from that 104 grams of ethyne will make $n(\text{CO}_2) = n(\text{C}) =3.71296\;\text{mol}$ of $\text{CO}_2$ .

Mass of all those $\text{CO}_2$ molecules:

$m = n\cdot M = 163\;\text{g}$ . (3 sig. fig. as in the mass of ethyne.)

7 0

3 years ago

What is the difference between ionic and covalent compounds?

k0ka [10]

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

D. All the above

Covalent compounds are always poor conductors of electricity while ionic compounds conduct electricity well when melted or dissolved.
Covalent compounds can be solid, liquid or gas, but ionic compounds are solids.
In covalent compounds the elements present are usually close together on the periodic table whereas in ionic compounds they are usually well separated.

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

<u>Ionic compounds are compounds that are formed from strong electrostatic interactions between ions.</u> Ionic bonding occurs between a nonmetal, which acts as an electron acceptor, and a metal, which acts as an electron donor. The atoms involved in ionic bonding lose or gain electrons and form positively or negatively charged ions.
<em><u>Ionic compound are good conductors of electricity both in molten and aqueous form,. while covalent compound are poor conductors of electricity.</u></em>
<u>Covalent compounds on the other hand are compounds that have bonds where electrons are shared between atoms.</u> These types bonds mostly occur between nonmetals or between two atoms of the same element.

8 0

3 years ago

A flask contains oxygen, carbon dioxide,

Grace [21]

Answer:

The total pressure is 25.7 atm

Explanation:

The total pressure is the sum of the pressures of the three gases in the flask.

total pressure=(11.4+5.6+8.7) atm

=25.7 atm

8 0

3 years ago

In which situation is no work considered to be done by a force?

Masja [62]

If the angle is either 0 or 180, that means that there is either negative or positive work, so A and D are not correct.

If the angle is 45, then there is still some work involved.

The only option where there is no work done by a force is B. when the angle is between the force and displacement is 90.

7 0

3 years ago

Read 2 more answers

The burning of a sample of propane generated 1 04.6 kJ of heat. All of this heat was used to heat 500.0 g of water that had an i

Paul [167]

Answer: 70.0°C

Explanation:

Quantity of heat = Mass * Specific heat * Change in temperature

Quantity of heat = 104.6 KJ

Mass = 500.0 g

Specific heat of water is 4.18 J/g°C

Change in temperature assuming final temperature is x = x - 20

Units should be in grams and joules:

104,600 = 500 * 4.18 * (x - 20)

104,600 = 2,090 * (x - 20)

x - 20 = 104,600/2,090

x = 104,600/2,090 + 20

x = 69.8

= 70.0°C

3 0

3 years ago