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erastovalidia [21]
3 years ago
13

1. Butane has a chemical formula CH4H10. The equation 2C4H10 + 13O2 → 8CO2 + 10H2O represents which of these?

Chemistry
1 answer:
Eddi Din [679]3 years ago
3 0

1) Answer is: B) A chemical change of butane into other substances.

Balanced chemical reaction: 2C₄H₁₀ + 13O₂ → 8CO₂ + 10H₂O.

This is chemical change (chemical reaction), because two new substances are formed (carbon dioxide and waters), the atoms are rearranged and the reaction is followed by an energy change.

This is not physical change, because the same substance is present before and after the psysical change, just with different form or state of matter.

2) Answer is: A) It increases.

Electrons can jump from one energy level to another, absorbing or emitting electromagnetic radiation with a frequency ν (energy difference of the levels).

Albert Einstein (1879-1955) proposed that a beam of light is a collection of discrete wave packets (photons) with energy hν, where h is Planck constant and ν is frequency.

Energy level 2 has higher energy than energy level 1.

3) Answer is: C) 400 kPa.

Boyle's Law (the pressure-volume law): volume of a given amount of gas held at constant temperature varies inversely with the applied pressure when the temperature and mass are constant.  

p₁V₁ = p₂V₂ (the product of the initial volume and pressure is equal to the product of the volume and pressure after a change).  

p₁ = 100 kPa; starting pressure.  

V₁ = 1.0 L., starting volume.

V₂ = 0.25 L; final volume, smaller than starting volume.

p₂ = ?; final pressure.  

100 kPa · 1 L = p₂ · 0.25 L.  

p₂ = 100 kPa · 1 L / 0.25 L.  

p₂ = 400 kPa.  

When volume goes up, pressure goes down.  

When volume goes down, pressure goes up.  

4) Answer is: C) HClO₄.

Balanced chemical reaction of dissociation of perchloric acid in water:

HClO₄(aq) → H⁺(aq) + ClO₄⁻(aq).

Ionic compounds (in this example perchloric acid) conduct electricity, because it dissociate in ions and ions conduct electicity.  

Ionic substances dissociate in water on cations and anions.  

Perchloric acid (HCO₄) is one of strongest inorganic acids.  

NH₃ is ammonia, NaOH is sodium hydroxide and NH₄OH ammonium hydroxide, all are bases.

5) Answer is: D) A and D.

A catalyst is a chemical species that is present at the beginning of a reaction and reappears at the end.

An intermediate forms during the reaction and disappears before the end.

Catalysis is the increase in the rate of a chemical reaction due to the participation of an additional substance called a catalyst.

Reactions occur faster with a catalyst because they require less activation energy.

6) Answer is: D) H2O has stronger intermolecular force of attraction.

Intermolecular forces are the forces between molecules or particles.

Because of hydrogen bonds, water has higher melting and boiling temperatures than H₂S.

In molecule of water there are dipole-dipole forces between negatively charged oxygen from one molecule of water and positively charger hydrogen of another molecule of water.

Hydrogen bond is an electrostatic attraction between two polar groups that occurs when a hydrogen atom (H), covalently bound to a highly electronegative atom such as flourine (F), oxygen (O) and nitrogen (N) atoms.

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An analytical chemist is titrating of a solution of nitrous acid with a solution of . The of nitrous acid is . Calculate the pH
Burka [1]

Answer:

pH = 2.69

Explanation:

The complete question is:<em> An analytical chemist is titrating 182.2 mL of a 1.200 M solution of nitrous acid (HNO2) with a solution of 0.8400 M KOH. The pKa of nitrous acid is 3.35. Calculate the pH of the acid solution after the chemist has added 46.44 mL of the KOH solution to it.</em>

<em />

The reaction of HNO₂ with KOH is:

HNO₂ + KOH → NO₂⁻ + H₂O + K⁺

Moles of HNO₂ and KOH that react are:

HNO₂ = 0.1822L × (1.200mol / L) = <em>0.21864 moles HNO₂</em>

KOH = 0.04644L × (0.8400mol / L) = <em>0.0390 moles KOH</em>

That means after the reaction, moles of HNO₂ and NO₂⁻ after the reaction are:

NO₂⁻ = 0.03900 moles KOH = moles NO₂⁻

HNO₂ = 0.21864 moles HNO₂ - 0.03900 moles = 0.17964 moles HNO₂

It is possible to find the pH of this buffer (<em>Mixture of a weak acid, HNO₂ with the conjugate base, NO₂⁻), </em>using H-H equation for this system:

pH = pKa + log₁₀ [NO₂⁻] / [HNO₂]

pH = 3.35 + log₁₀ [0.03900mol] / [0.17964mol]

<h3>pH = 2.69</h3>
8 0
3 years ago
One sound is loud and another is quieter. What must be different about these two sound waves?
tankabanditka [31]
Loudness of the sound depends on the "Amplitude" as loudness is different for two waves, their Amplitude must be different

In short, Your Answer would be "Amplitude"

Hope this helps!
3 0
3 years ago
Hydrogen iodide is not produced by the same method is for hydrogen chloride why with reaction​
Masja [62]

Using Phosphoric acid will work perfectly for producing Hydrogen halides because its not an Oxidizing agent. ...

Using an ionic chloride and Phosphoric acid

H3PO4 + NaCl ==> HCl + NaH2PO4

H3PO4 + NaI ==> HI + NaH2PO4

H2SO4 + NaCl ==> HCl + NaHSO4

This method(Using H2So4) will work for all hydrogen hydrogen halide except Hydrogen Iodide and Hydrogen Bromide.

The Sulphuric acid won't be useful for producing Hydrogen Iodide because its an OXIDIZING AGENT. Whist producing the Hydrogen Iodide... Some of the Iodide ions are oxidized to Iodine.

2I-² === I2 + 2e-

5 0
3 years ago
Which information is revealed in a chemical formula?
wariber [46]
I think the answer is B
7 0
2 years ago
Read 2 more answers
Write names of one diatomic and tetra -atomic element.
Lady bird [3.3K]
Nitrogen is diatomic which exists as N2. This is because of its small size and high electronegativity.

Phosphorus is tetra atomic which exists as P4. 
7 0
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