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Presentation On Haber Process And Contact Process

Published in: Chemistry | Science
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This PPT is suitable for the IGCSE and O Level Chemistry students. It only provides theoretical background of the topic. The worksheets and topical questions will be discussed during the tutoring sessions

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  1. Haber Process and Contact Process Chemistry (IGCSE / O-Level)
  2. What will you learn in this lesson? • Details of Haber process and Contact process • Sources of reactant materials for both the processes • Typical conditions for the Haber process and Contact process • Typical conditions stated are used in the Haber process and in the Contact process, including safety considerations and economics in terms of rate of reaction and position of equilibrium,
  3. Haber Process The Haber Process is used to commercially manufacture ammonia (NH3) gas. This process was developed by the scientist Fritz Haber. Common Uses of Ammonia: fertilisers 75% nitric acid Others
  4. Conditions for the Haber Process N2(g) + 3Hd(g) * 2NHstg) Because of its importance production of ammonia is studied at wide range of conditions of temperatures and pressures. 39 'C sso•c
  5. Conditions for the Haber Process (contd.) To shift the equilibrium to the right or to increase the yield of ammonia, La Chatelier's Principle is used flow pressure hiOh temperature Whieb changes improve the yield of NHS? KAKI pressure low temperature
  6. Conditions for the Haber Process (contd.) Changing the Pressure: 2 moles 4 moles With increased pressure, there will be a shift to the right. More ammonia will be formed to reduce the number of molecules in the mixture and oppose the increasing the pressure. Modern industrial plants use the temperature of 20000 kPa / 200 atm Higher pressure, increases the rate of reaction Increasing pressure, increase the concentration of reactants, increasing the rate at which equilibrium is achieved Pressure can be increased more but higher pressure reaction vessels are expensive and are at the verge of explosion
  7. Conditions for the Haber Process (contd.) Changing the Temperature: Nz(g) + 3H2(g) 2NHs(g) exothermic — he* given out 2NH3(g) N2(g) + 3Hi(g) — heat taken in If lower temperature, more ammonia will be produced. An optimum or compromise temperature of about 450 oc is used to produce enough ammonia at acceptable rate. A temperature that gives sufficient product and a reasonable and economic rate of reaction
  8. Conditions for the Haber Process (contd.) Reducing the Concentration of Ammonia: If the system was at equilibrium, some of the ammonia is removed, more ammonia would be produced to replace what had been taken away. Ammonia has higher boiling point than nitrogen and hydrogen. It also condenses easily, leaving nitrogen and hydrogen still as gases. Gas mixture is removed from reaction chamber when the percentage of ammonia is about 15% Boiling nitrogen (N2) hydrogen (Ha) ammonia (NHS)
  9. Conditions for the Haber Process (contd.) Use of a Catalyst: Finely divided iron can be used as a catalyst industrially. Catalyst shortens the time taken to reach equilibrium by increasing the rates of both the forward and reverse reactions. It does not alter the equilibrium concentration of reactant and product gases
  10. Industrial Plant for the Haber Process + hy&wn arnmon_ta N2(g) + 3H2(g) 2NHa(g) Nitrogen is obtained from air by fractional distillation Hvdrogen is obtained from the steam-reforming of the natural gas, or from the breakdown of hydrocarbons such as, ethane natural gas in.the presence of nickel catalystforms hydrogen and carbon monoxide; —cow methane hydrogen The od\dgøi$on the and is therefore removed by reac$ng with move steam. be Obtained from, the ethane using high and - ChLfg) — + ethane ethene bydrogen
  11. Industrial Plant for the Haber Process (contd.) The process is reversible and does not go to completion. The 'Scrubbed' means cleaned of contaminants proportion of ammonia in mixture is about 15% The boiling point of ammonia is higher that nitrogen and hydrogen. So, it condenses easily and unchanged remaining nitrogen and hydrogen gases are re-circulated to yield almost 98% NH3
  12. Industrial Plant for the Haber Process (contd.) The essential cond1tEons used in the Haber process are: • and Ha are mixed in a ratio of 1 : 3 • an optimum (or compromise) temperature of 450 oc • a pressure of 20 kPa (200 atmospheres) • a catalyst cf finely civided iron. The ammonia is condensed out of the reaction mixture and the remaining N2 and Ha recycled.
  13. Contact Process Sulfuric acid is the major product of chemical industry. Industrially, sulfuric acid is made from sulfur dioxide in the Contact process. The main reaction in the Contact process is the reversible reaction between sulfur dioxide and oxygen to form sulfur trioxide. exothermtc (AH —197 gjymdl)
  14. Conditions for Contact Process The essential conditions used in the Contact process are: • a compromise (optimum) temperature of about 450 oc • a catalyst of vanadlum(V) oxide (V205) • an operating pressure of 200 kPa. What will happen if the temperature is: a) below optimum temperature b) above optimum temperature
  15. Industrial Plant for the Contact Process The raw materials needed for the Contact process are sulfur, air and water. Sulfur can be mined in various parts of the world, but large quantities are now obtained by removing the impurities from fossil fuels. SUfLr diox& re*ired the Contact process is obtained industrially by bumTng sulfur or roasting sulfide ores such as zinc blende (Zns). S(s) + Oe(g)- S02(g) + metal oxide -1• sulfilr dioxide 2zus(s) + 302(g) 2zno(s) + 2S02(g)
  16. Industrial Plant for the Contact Process (contd.) sulfur burnt to form sulfur dioxide + — s0Jg) 2SOßgi — ascrc. kPa van•dmrnm catalyst ciluted when Sulfur dioxide produced is dissolved in 98% sulfur acid, instead of water to avoid acid mist 98.5% sulfuric acid (also known as oleum) is transported and diluted at the destination Sulfuric acid is important for fertilizer industry because it is needed to make ammonium sulfate and phosphoric acid
  17. Practice Questions oxygen reae both nRrogen and nitrogen(ll) oxide (No) in reverstble rezctlons. 4 5 6 a b N2(g) + 02(g) 2NO(g) 2NO(g) + 02(g) 2N02(g) Describe how an increase in pressure Will affect the pogition of equlibrium of I the reactlon betw-een nftrogen and oxygen ü the reaction oxygon and nitrogen(ll) oxida, The reaction b*ween nitrogen and oxygen endotherrnlc. Describe how an increase In temperature wnl affect the rea&lon. Explain answer. The av*labllty Cf raw materials Is essenttal for an tndustrtal pmcess. a b c a b c d How is hydrogen obtained for use ín the Haber process? Describe tWO af suYur dioxlde for the Contact procesg. What Is the cmmmon scurce of the nttrogen and oxygen requtred for the Haber and Contact processes? What are the cordtions 'Sed fer the Haber procesS7 Will increadng the pres.re In the Haber process produce more or less ammonla? What wauld be the effect of increaslng the temperature in the Haber process on the level of ammonia produced? Why tha Lnv•acted gas•• re-circulated?