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GaryK [48]
2 years ago
5

9- Which pair of formulae represents two alkanes? (1 mark)

Chemistry
1 answer:
Ksenya-84 [330]2 years ago
8 0

Answer:

A) CH4 and C8H18

Explanation:

  • General Formula for an Alkane = CnH2n+2

  • This means for every number of Carbon (C) atoms, there are twice as many Hydrogen (H) atoms with an additional two added onto that.

  • Therefore, if there is one Carbon Atom, and we multiply that by two, and then add an additional two, we get 4 Hydrogen atoms, so CH4, which is our first Formulae

  • Secondly, if we have eight Carbon Atoms, and we multiple that by two (16), and then add an additional two, we get 18 Hydrogen atoms, so C8H18, which is our second Formulae

  • The other Formulas do not follow this 'General Formula'
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a glass container was initially charged with 1.50 mol of a gas sample at 3.75 atm and 21.7C. some of the gas was release as the
butalik [34]

Answer:

0.39 mol

Explanation:

Considering the ideal gas equation as:

PV=nRT

where,  

P is the pressure

V is the volume

n is the number of moles

T is the temperature  

R is Gas constant having value = 0.0821 L.atm/K.mol

At same volume, for two situations, the above equation can be written as:-

\frac {{n_1}\times {T_1}}{P_1}=\frac {{n_2}\times {T_2}}{P_2}

Given ,  

n₁ = 1.50 mol

n₂ = ?

P₁ = 3.75 atm

P₂ = 0.998 atm

T₁ = 21.7  ºC

T₂ = 28.1 ºC

The conversion of T( °C) to T(K) is shown below:

T(K) = T( °C) + 273.15  

So,  

T₁ = (21.7 + 273.15) K = 294.85 K  

T₂ = (28.1 + 273.15) K = 301.25 K  

Using above equation as:

\frac{{n_1}\times {T_1}}{P_1}=\frac{{n_2}\times {T_2}}{P_2}

\frac{{1.50\ mol}\times {294.85\ K }}{3.75\ atm}=\frac{{n_2}\times {301.25\ K  }}{0.998\ atm}

n_2=\frac{{1.50}\times {294.85}\times 0.998}{3.75\times 301.25}\ mol

Solving for n₂ , we get:

n₂ = 0.39 mol

7 0
3 years ago
By increasing the length of heat exchanger, the effectiveness and cold stream output temperature of the heat exchanger
Dominik [7]

Answer:

Effectiveness and cold stream output temperature of the heat exchange Increases. So, Answer is b) Increases.

Explanation:

We have a heat exchanger, and it is required to compare the effectiveness and cold stream output if the length is increased.

Heat exchangers are engineering devices used to transfer energy. Thermal energy is transferred from Fluid 1 - Hot fluid (HF) to a Fluid 2 - Cold Fluid (CF). Both fluids 1 and 2 can flow with different values of mass flow rate and different specific heat. When the streams go inside the heat exchanger Temperature of Fluid 1 (HF) will decrease, at the same time Temperature of the Fluid 2 (CF) will increase.

In this case, we need to analyze the behavior taking into account different lengths of heat exchangers. If the length of the heat exchanger increases, it means the transfer area will increases. Heat transfer will increase if the transfer area increases. In this sense, the increasing length is the same than increase heat transfer.

If the heat transfer increases, it means Fluid 1 (HF) will reduce its temperature, and at the same time Fluid 2 (CF) will increase its temperature.

Finally, Answer is b) Effectiveness and cold stream output temperature increases when the length of the heat exchanger is increased.

5 0
3 years ago
MnO2 + 4HCl reacts to form MnCl2 + CL2 + 2H2O If .86 mol of MnO2 and 48.2 g of HCl react, which reactant is the limiting reagent
Katen [24]
HCl:
<span>
m=48,2g
M=36,5g/mol

n = m/M = 48,2g / 36,5g/mol = 1,32mol

1mol          : 4mol
MnO</span>₂        + 4HCl ⇒ MnCl₂ + Cl₂ + 2H₂O
0,86mol     :  1,32mol
                     limiting reagent 
0,33 will react

HCl is limiting reagent.
6 0
3 years ago
g The boiling of water is a Question 4 options: chemical and physical damage chemical change because a gas (steam) is given off
Strike441 [17]

Answer:

physical change because the gaseous water is chemically the same as the liquid

Explanation:

Matter can be defined as anything that has mass and occupies space. Any physical object that is found on earth is typically composed of matter. Matter are known to be made up of atoms and as a result has the property of existing in states.

Generally, matter exists in three (3) distinct or classical phases and these are; solid, liquid and gas.

A physical change can be defined as a type of change that only affects the physical form of a chemical substance (matter) without having any effect on its chemical properties. Thus, a physical change would only affect the physical appearance and properties of a chemical substance (matter) but not its chemical properties.

This ultimately implies that, a physical change result in a change of matter from one form or phase (liquid, solid or gas) to another without a corresponding change in chemical composition.

Hence, the boiling of water is considered to be a physical change because the gaseous water is chemically the same as the liquid i.e there isn't any changes in chemical composition of water when boiling.

8 0
3 years ago
What intermolecular force attracts two non polar molecules to each other
Salsk061 [2.6K]

The intermolecular force that attracts two nonpolar molecules is London dispersion forces, which are also called induced dipole-induced

3 0
3 years ago
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