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andriy [413]
3 years ago
9

Tick (√) the statements that are correct.

Chemistry
1 answer:
BARSIC [14]3 years ago
7 0

b) (√)

c)(✓)

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Kemmi Major does some experimental work on the combustion of sucrose: C12H22O11(s) 12 O2(g) → 12 CO2(g) 11 H2O(g) She burns a 0.
Pavlova-9 [17]

Answer: 5.81\times 10^6J/mol

Explanation:

Heat of combustion is the amount of heat released when 1 mole of the compound is completely burnt in the presence of oxygen.

C_{12}H_{22}O_{11}(s)+12O_2\rightarrow 12CO_2(g)+11H_2O(g)

To calculate the moles, we use the equation:

\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}=\frac{0.05392g}{342g/mol}=1.577\times 10^{-4}moles

Thus 1.577\times 10^{-4}moles of sucrose releases =  916.6 J of heat

1 mole of sucrose releases =\frac{916.6}{1.577\times 10^{-4}}\times 1=5.81\times 10^6J of heat

Thus ∆H value for the combustion reaction is 5.81\times 10^6J/mol

6 0
3 years ago
What is the main advantage of using ethanol
natka813 [3]

Answer:

Overall, ethanol is considered to be better for the environment than petrol. Ethanol-fuelled vehicles produce lower carbon dioxide emissions, and the same or lower levels of hydrocarbon and oxides of nitrogen emissions.

Explanation:

5 0
3 years ago
In the reaction CuO(s) + CO2(g) → CuCO3(s), a. CO2 is the Lewis acid and CuCO3 is its conjugate base. b. O2– acts as a Lewis bas
adoni [48]

<u>Answer:</u> The correct answer is Option d.

<u>Explanation:</u>

According to Lewis acid-base concept:

The substance which is donating electron pair is considered as Lewis base and the substance which is accepting electron pair is considered as Lewis acid.

For the given chemical reaction:

CuO(s)+CO_2(g)\rightarrow CuCO_3(s)

CO_2 is accepting electron pair and is getting converted to CO_3^{2-}. Thus, it is considered as Lewis acid.

O^{2-} present in CuO is a Lewis base because it is donating electron pair.

Thus, the correct answer is Option d.

4 0
3 years ago
. An atom of nitrogen has an atomic
GrogVix [38]

Here's the Answer !

Atomic number = no. of electrons = no. of protons, therefore :

  • no. of electrons = 7

  • no. of protons = 7

and mass number = no. of protons + no. of neutrons

so,

  • 7 + no. of neutrons = 14

  • no. of neutrons = 7
5 0
3 years ago
Gold is alloyed (mixed) with other metals to increase its hardness in making jewelry.
KiRa [710]

Answer:

A) 54.04%

B) 13-karat

Explanation:

A) From the problem we have

<em>1)</em> Mg + Ms = 9.40 g

<em>2)</em> Vg + Vs = 0.675 cm³

Where M stands for mass, V stands for volume, and g and s stand for gold and silver respectively.

We can rewrite the first equation using the density values:

<em>3)</em> Vg * 19.3 g/cm³ + Vs * 10.5 g/cm³ = 9.40

So now we have<em> a system of two equations</em> (2 and 3) <em>with two unknowns</em>:

We <u>express Vg in terms of Vs</u>:

  • Vg + Vs = 0.675 cm³
  • Vg = 0.675 - Vs

We <u>replace the value of Vg in equation 3</u>:

  • Vg * 19.3 + Vs * 10.5 = 9.40
  • (0.675-Vs) * 19.3 + Vs * 10.5 = 9.40
  • 13.0275 - 19.3Vs + 10.5Vs = 9.40
  • -8.8 Vs + 13.0275 = 9.40
  • <u>Vs = 0.412 cm³</u>

Now we <u>calculate Vg</u>:

  • Vg + Vs = 0.675 cm³
  • Vg + 0.412 cm³ = 0.675 cm³
  • Vg = 0.263 cm³

We <u>calculate Mg from Vg</u>:

  • 0.263 cm³ * 19.3 g/cm³ = 5.08 g

We calculate the mass percentage of gold:

  • 5.08 / 9.40 * 100% = 54.04%

B)

We multiply 24 by the percentage fraction:

  • 24 * 54.04/100 = 12.97-karat ≅ 13-karat
4 0
3 years ago
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