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3 years ago

Do we generally break chemical bonds when we cool molecules?

1 answer:

7 0

The breaking of chemical bonds never releases energy to the external environment. Energy is only released when chemical bonds are formed. In general, a chemical reaction involves two steps: 1) the original chemical bonds between the atoms are broken, and 2) new bonds are formed. These two steps are sometimes lumped into one event for simplicity, but they are really two separate events. For instance, when you burn methane (natural gas) in your stove, the methane is reacting with oxygen to form carbon dioxide and water.

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Give the number of significant figures indicated 6.695

Genrish500 [490]

3 significant figures

5 0

3 years ago

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In which of the following sets are the charges given correctly for all the

Ronch [10]

Answer:

B) K⁺, Sr²⁺ , O²⁻

Explanation:

Potassium is present in group one. It is alkali metal and have one valance electron.Potassium need to lose its one valance electron and form cation to get complete octet.

That's why it shows K⁺.

Sr is alkaline earth metal. It is present in group two. It has two valance electrons. Strontium needed to lose its two valance electrons and get stable electronic configuration.

When it loses its two valance electrons it shows cation with charge of +2.

Sr²⁺

Oxygen is present in group 16. It has sex valance electrons. It needed two more electrons to complete the octet. That's why oxygen gain two electron and form anion with a charge of -2.

O²⁻

3 0

3 years ago

Binary compound of oxygen and an unknown element,X, has the formula XO2 and is 69.55 mass % oxygen, what is the weight of elemen

marissa [1.9K]

Answer:

Weight of element X = 14.01 gram

Explanation:

Mass percentage is calculated by using :

$Percent =\frac{Mass\ of\ element}{Total\ mass}\times 100$

$O\ Percent=\frac{Mass\ of\ O}{Total\ mass\ of\ XO2}\times 100$

Mass of O = 16.0 gram

let mass of X = X grams = ?

Mass of XO2 = mass of X + 2(mass of O)

Mass of XO2 = X + 2(16)

Mass of XO2 = X + 32

Total mass of O in the compound = 2(16) = 32 grams

Percent O = 69.55 %

$Percent\ O =\frac{Mass\ of\ O}{Total\ mass\ of\ XO2}\times 100$

$69.55=\frac{32}{X+32}\times 100$

$\frac{69.55}{100}=\frac{32}{X+32}$

$0.6955=\frac{32}{X+32}$

$0.6955\times (X+32)=32$

$0.6955X+ 22.256=32$

$0.6955X=9.744$

$X=\frac{9.744}{0.6955}$

$X =14.01$

weight of element X = 14.01 gram

14.01 is mass of nitrogen N

The correct formula of this element is NO2

6 0

3 years ago

2 . what is the formula weight of (nh4)2so4? 118 amu 116 amu 100 amu 132 amu

Nataly [62]

Hey there!

(NH₄)₂SO₄ = 14 * 2 + 1 * 8 + 32+ 16 * 4 => 132 amu

6 0

3 years ago

An empty 25.00 mL volumetric flask has a mass of 20.550 g. When it is partially filled with metal pellets, the mass is 130.278 g

nasty-shy [4]

<span>Density is a value for mass, such as kg, divided by a value for volume, such as m^3. Density is a physical property of a substance that represents the mass of that substance per unit volume. We calculate as follows:

Density = (130.278 - 20.550) / (142.419 - 130.278)/0.7918 = 7.16 g/mL</span>

3 0

3 years ago

Read 2 more answers