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Mandarinka [93]
3 years ago
5

Metals and nonmetals all lesson explanation for class 8​

Chemistry
1 answer:
WINSTONCH [101]3 years ago
7 0

Answer:

Metalloids elements whose properties are intermediate between those of metals and solid nonmetals or semiconductors.

Some examples:

Chemical element.

Boron.

Semiconductor.

Arsenic.

Silicon.

Selenium.

Antimony.

Germanium.

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A chemist measures the energy change ΔH during the following reaction: C3H8 (g) +5O2 (g) →3CO2 (g) +4H2O (l) =ΔH−2220.kJ Use the
statuscvo [17]

Answer:

The reaction is exothermic.

Yes, released.

The heat released is 4,08x10³ kJ.

Explanation:

For the reaction:

C₃H₈(g) + 5O₂(g) → 3CO₂(g) + 4H₂O(l)

The ΔH is -2220 kJ, As ΔH is <0, <em>The reaction is exothermic.</em>

As the reaction is exothermic, the heat of the reaction will be <em>released.</em>

The heat released in 81,0g is:

81,0g C₃H₈×\frac{1mol}{44,1g}×\frac{2220kJ}{1mol}= <em>4,08x10³ kJ</em>

<em>-Using molar mass of C₃H₈ to convert mass to moles and knowing that there are released 2220 kJ per mole of C₃H₈-</em>

I hope it helps!

3 0
3 years ago
At 100 degrees Celsius, the ion product for pure water is Kw= 51.3*10^-14. What is the pOH of water at this temperature? A) 7.00
Levart [38]

7.86 is the pOH of water at this temperature of 100 degrees celsius.

Option E is the right answer.

Explanation:

Data given:

Kw = 51.3 x 10^{-14}

pOH = ?

we know that pure water is neutral and will have pH pf 7.

The equation for relation between Kw and H+ and OH- ion is given by:

Kw = [H+] [OH-}

here the concentration of H+ ion and OH- ion is equal

so, [H+]= [OH-]

Putting the values in the equation of Kw

pKw = -log[Kw]

pKw = -log [51.3 x 10^{-14}]

pKw = 12.28

since H+ ion OH ion concentration is equal the pH of water is half i.e. 6.14

Now, pOH is calculated by using the equation:

14 = pOH + pH

14- 6.14 = pOH

pOH = 7.86

8 0
3 years ago
Potassium hydroxide is classified as an arrhenius base because koh contains
mixas84 [53]

Answer: hydroxide ions

Explanation:

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According to the Bronsted Lowry conjugate acid-base theory, an acid is defined as a substance which donates protons and a base is defined as a substance which accepts protons.

According to the Lewis concept, an acid is defined as a substance that accepts electron pairs and base is defined as a substance which donates electron pairs.

As KOH can give hydroxide ions on dissociation , it is considered as arrhenius base.

KOH\rightarrow K^++OH^-

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KonstantinChe [14]

Answer:

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Partes de su teoría tuvieron que ser modificadas con base en el descubrimiento de las partículas subatómicas y los isótopos.

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What is the term for a fine grained soil deposited by the wind
balandron [24]

I think it is called a loess. Please correct me if I am wrong.

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