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forsale [732]
2 years ago
7

Can you please help on 17 and 18 pleaseeee

Chemistry
1 answer:
nadezda [96]2 years ago
6 0

Answer:

17. Yes, it represents a chemical reaction. This is because new substances were formed from the original substance.

18. (a) Formation of new substances

(b) Evolution or absorption of large quantity of heat

(c)Change in mass of substances

Explanation:

17. In the model above, molecules of a compound of carbon and hydrogen (molecular formula is C2H6) combines with molecular oxygen (O2) to produce two new substances; a compound composed of two oxygen atoms and one carbon atom (CO2) and another compound composed of two atoms of hydrogen and one atom of oxygen (H2O). Since the new substances formed are completely different from the original substances, it a chemical reaction. Also, a large volume of heat would have been given off.

18. To determine if a chemical reaction has occurred, the following observations can be looked out for.

a. Formation of new substances different entirely from the original substances

b. Evolution or absorption of large quantity of heat during the change. Check whether the vessel containing the substances gets hotter or colder.

c. Change in mass of substances. Since new substances are formed in a chemical reaction, there is usually a significant change in mass of the products and reactants.

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What is the new concentration of a solution of CaSO3 if 10.0 mL of a 2.0 M CaSO3 solution is diluted to 100 ml?
kifflom [539]

Answer: The new concentration of a solution of CaSO_{3} is 0.2 M 10.0 mL of a 2.0 M CaSO_{3} solution is diluted to 100 mL.

Explanation:

Given: V_{1} = 10.0 mL,      M_{1} = 2.0 M

V_{2} = 100 mL,           M_{2} = ?

Formula used to calculate the new concentration is as follows.

M_{1}V_{1} = M_{2}V_{2}

Substitute the values into above formula as follows.

M_{1}V_{1} = M_{2}V_{2}\\10.0 mL \times 2.0 M = M_{2} \times 100 mL\\M_{2} = 0.2 M

Thus, we can conclude that the new concentration of a solution of CaSO_{3} is 0.2 M 10.0 mL of a 2.0 M CaSO_{3} solution is diluted to 100 mL.

5 0
2 years ago
Give the structure that corresponds to the following molecular formula and 1H NMR spectrum: C4H10O2: δ 1.36 (3H, d, J = 5.5 Hz);
kondor19780726 [428]

Answer:

For the determination of a structure through its NMR it is necessary to know its molecular formula as well as the delta values, its coupling and the shift of each signal.

The separation produced is called coupling constant J and is measured in Hz. If the split is produced by two equal protons (equal J) a triple signal known as triplet is produced and if produced by three equal protons, the signal is quadruple and is known as quadruplet. The magnitude of the coupling is varied, depending on the relative disposition of the coupled protons (elevations that separate them, arrangement, spatial arrangement)

OH CH2 CH2 CH2 CH2 OH

(A)   (B)   (C)

1,4-butanediol

In the case of the molecule to study the signal at 1.36 shows a doublet, which corresponds to the hydrogen (C), is split in two for each different proton on the same carbon or on neighboring carbons.

At 3.32 ocurrs a singlet, wich belong to hidrogen (B). The last signal is a quintet, at 4.63 belonging to the hydrogen (C)

Explanation

Nuclear magnetic resonance NMR is a physical phenomenon based on the mechanical-quantum properties of atomic nuclei. NMR also refers to the family of scientific methods that explore this phenomenon to study molecules, macromolecules, as well as tissues and whole organisms.

NMR takes advantage of the fact that atomic nuclei resonate at a frequency directly proportional to the force of a magnetic field exerted, in accordance with the Larmor precession frequency equation, to subsequently disturb this alignment with the use of an alternating magnetic field, of orthogonal orientation.

The behavior of the nuclei in the magnetic field can be influenced in multiple ways, to give different types of information, but the basic information obtained is:

  • Frequency at which each particular nuclei comes out, displacement.
  • Number of nucleis of each type, integral.
  • Number and arrangement of nearby nuclei, multiplicity.
6 0
2 years ago
What mass of barium carbonate can be produced when 100.0 mL of a 0.100 M solution of barium chloride is mixed with 100.0 mL of a
valentinak56 [21]
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3 0
2 years ago
A buffer solution contains 0.479 M NaHCO3 and 0.342 M Na2CO3. Determine the pH change when 0.091 mol HNO3 is added to 1.00 L of
pshichka [43]

Answer:

ΔpH = 0.20

Explanation:

The buffer of HCO₃⁻ + CO₃²⁻ has a pka of 10.2

HCO₃⁻ ⇄ H⁺ + CO₃²⁻

There are 0.479moles of NaHCO₃ and 0.342moles of Na₂CO₃.

Using Henderson-Hasselbalch formula:

pH = pka + log [Base] / [Acid]

pH = 10.2 + log 0.342mol / 0.479mol

<em>pH = 10.05</em>

NaOH reacts with HCO₃⁻ producing CO₃²⁻, thus:

NaOH + HCO₃⁻ → CO₃²⁻ + H₂O + Na⁺

0.091 moles of NaOH produce the same moles of CO₃²⁻ and consume HCO₃⁻. Moles of these species are:

CO₃²⁻: 0.342mol + 0.091mol: 0.433mol

HCO₃⁻: 0.479mol - 0.091 mol: 0.388mol

Using Henderson-Hasselbalch formula:

pH = pka + log [Base] / [Acid]

pH = 10.2 + log 0.433mol / 0.388mol

pH = 10.25

That means change of pH, ΔpH is:

ΔpH = 10.25 - 10.05 = <em>0.20</em>

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I hope it helps!

3 0
2 years ago
Why does every chemical reaction require a certain amount of activation energy?
Margaret [11]

Answer:

Forming the activated complex requires energy.

Explanation:

4 0
3 years ago
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