1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Setler79 [48]
3 years ago
10

It is proposed to use Liquid Petroleum Gas (LPG) to fuel spark-ignition engines. A typical sample of the fuel on a volume basis

consists of: 70% propane C3H8; 5% butane C4H10; and 25% propene C3H6 The higher heating values of the fuels are 50.38 MJ/kg for propane, 49.56 MJ/kg for butane, and 48.95 MJ/kg for propene. a) Work out the overall combustion reaction for stoichiometric combustion of 1 mole of LPG with air, and determine the stoichiometric F/A and A/F ratios. b) What are the higher and lower heating values per unit mass of LPG?
Chemistry
1 answer:
Norma-Jean [14]3 years ago
7 0

Answer:

a)

The overall  balanced combustion  reaction is written as :

0.7C_3H_8 \ + \ 0.05C_4H_{10} \ + \ 0.25 C_3H_6 \ + \ x(O_2 \ + \ 3.76N_2) ---> 3.05CO_2  \ + \ 3.8H_2O \ + \ 18.612N_2

(F/A)_{stoichiometric} = 0.0424

(A/F)_{stoichiometric} = 23.562

b)

the higher heating values (HHV)_f per unit mass of LPG = 49.9876 MJ/kg

the lower heating values (LHV)_f per unit mass of LPG = 46.4933 MJ/kg

Explanation:

a)

The stoichiometric equation can be expressed as :

0.7C_3H_8 \ + \ 0.05C_4H_{10} \ + \ 0.25 C_3H_6 \ + \ x(O_2 \ + \ 3.76N_2) ---> aCO_2  \ + \ bH_2O \ + \ cN_2

Now, equating the coefficient of carbon; we have:

(0.7×3)+(0.05×4)+(0.25×3) = a

a = 3.05

Also, Equating the coefficient of hydrogen : we have:

(0.7 × 8) +(0.05 × 10) + ( 0.25 × 6) = 2 b

2b = 7.6

b = 3.8

Equating the coefficient of oxygen

2x = 2a + b

x = \frac{2a+b}{2} \\ \\ x =  \frac{2(3.05)+3.8}{2} \\ \\ x = 4.95

Equating the coefficient of Nitrogen

c = 3.76x \\ \\ c = 3.76 *4.95 \\ \\ c = 18.612

Therefore, The overall  balanced combustion  reaction can now be written as :

0.7C_3H_8 \ + \ 0.05C_4H_{10} \ + \ 0.25 C_3H_6 \ + \ x(O_2 \ + \ 3.76N_2) ---> 3.05CO_2  \ + \ 3.8H_2O \ + \ 18.612N_2

Now;  To determine the stoichiometric F/A and A/F ratios; we have:

(F/A)_{stoichiometric} = \frac{n_f}{n_a } \\ \\  (F/A)_{stoichiometric} = \frac{1}{4.95*(1+3.76)} \\ \\ (F/A)_{stoichiometric} = 0.0424

(A/F)_{stoichiometric} = \frac{n_a}{n_f } \\ \\  (A/F)_{stoichiometric} = \frac{4.95*(1+3.76)}{1} \\ \\ (A/F)_{stoichiometric} = 23.562

b)

What are the higher and lower heating values per unit mass of LPG?

Let calculate the molecular mass of the fuel in order to determine their mass fraction of the fuel components.

Molecular mass of the fuel M_f = (0.7*M_{C_3H_5} ) + (0.05 *M_{C_4H_{10}}) + (0.25*M _{C_3H_6})

= 30.8 + 2.9 + 10.5

= 44.2 kg/mol

Mass fraction of the fuel components can now be calculated as :

m_{C_3H_8} = \frac{30.8}{44.2} \\ \\ m_{C_3H_8}  = 0.7 \\ \\ \\  m_{C_4H_{10}} = \frac[2.9}{44.2} \\ \\ m_{C_4H_{10}} = 0.06  \\  \\ \\ m_{C_3H_6} = \frac{10.5}{44.2} \\ \\ m_{C_3H_6}  = 0.24

Finally; calculating the higher heating values (HHV)_f per unit mass of LPG; we have:

(HHV)_f=(0.7 * HHV_{C_3H_8}) + (0.06 *HHV_{C_4H_{10}})+(0.24*HHV_{C_3H_6} \\ \\ (HHV)_f=(0.7*50.38)+(0.06*49.56)+(0.24*48.95) \\ \\ (HHV)_f=49.9876 \ MJ/kg

calculating the lower heating values (LHV)_f per unit mass of LPG; we have:

(LHV)_f = (HHV)_f - \delta H_w \\ \\  (LHV)_f = (HHV)_f  - [\frac{m_w}{m_f}h_{vap}] \\ \\ (LHV)_f   = 49.9876 \ MJ/kg -  [\frac{3.8*18}{44.2}*2.258 \ MJ/kg]  \\ \\ (LHV)_f = 46.4933 \ M/kg

You might be interested in
You burn a 15g jellybean to warm 50 mL of water, which increases the temperature of the water 25 °C. How many calories of heat a
Juli2301 [7.4K]

Answer:

Q = 375\,cal

Explanation:

The quantity of heat transfered from the jellybean to the water is:

Q = \rho\cdot V \cdot c\cdot \Delta T

Q = \left(1\,\frac{g}{cm^{3}}\right)\cdot (15\,cm^{3})\cdot \left(1\,\frac{cal}{g\cdot ^{\circ} C} \right)\cdot (25\,^{\circ}C )

Q = 375\,cal

7 0
2 years ago
Read 2 more answers
Write a balanced chemical equation for the reaction that occurs when copper (II) hydroxide decomposes into copper (II) oxide and
olchik [2.2K]
Cu(OH)2 ------> CuO + H2O
8 0
3 years ago
At what point on the hill will the car have zero gravitational potential energy? A) Half-way down the hill. B) At the top of the
rewona [7]
The answer is C...........
8 0
3 years ago
HELPPPP STILLLL!!!! SCIENCE!!!!
Vadim26 [7]

Answer: the third one

Explanation:

4 0
3 years ago
PLEASE HELP...with single replacement reaction w/ activity series
Blizzard [7]

Answer : The balanced chemical reaction will be:

AuI_4+2Br2\rightarrow AuBr_4+2I_2

Explanation :

Single replacement reaction : A chemical reaction in which the more reactive element replace the less reactive element.

It is represented as,

A+BC\rightarrow AC+B

In this reaction, A is more reactive element and B is less reactive element.

As per question, when gold (IV) iodide react with bromine to give gold (IV) bromide and iodine.

The balanced chemical reaction will be:

AuI_4+2Br2\rightarrow AuBr_4+2I_2

8 0
3 years ago
Other questions:
  • Elements are pure substances made up of _____.
    15·2 answers
  • Hey can u help me with my hw? I’ll send a pic.
    15·1 answer
  • 6.7 mL of a ptassium chlorid solution was added to a 54.730 gevaporating dish. The combination weight 61.945 g. Afterevaporation
    5·1 answer
  • . What factors should Margaret NOT consider when deciding how much powder to add to her glass of water?
    7·1 answer
  • 3 facts about transfer of enegry
    12·2 answers
  • A 2.500g sample of compound containing only Carbon and Hydrogen is found containing 2.002g of Carbon. Determine the empirical fo
    13·1 answer
  • In a car engine gasoline is burning to create mechanical energy which of the following statements is true? A. Some energy is los
    11·1 answer
  • Metallic Bond<br> When nitrogen shares electrons with oxygen, what kind of bond is made?
    5·1 answer
  • Please help, so confused!!
    14·1 answer
  • EXPLAIN How would you explain the difference between single displacement and
    12·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!