Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
Q. What do you understand by dissolved oxygen in water? How does it create trouble in boiler? Give chemical methods with suitable reactions to remove it from the water.
Ans.
Presence of dissolved oxygen: At room temperature about 8 ppm of dissolved oxygen is present in water. Oxygen enters the boiler through raw make up water. When water containing the free gas is evolved under prevailing high temperature of boiler and attacks the boiler material.
2Fe + 2H2O + O2 = 2Fe (OH) 2
4Fe (OH) 2 + O2 + 2H2O = 2[Fe2O3.2H2O]
Removal of dissolved oxygen:
1. Chemical means: Oxygen can be removed by adding calculated amounts of certain chemicals such as Na2SO3, Na2S and N2H4.
Na2SO3 + O2 = 2Na2SO4
Na2S + 2O2 = Na2SO4
However, the sodium sulphate so formed may decompose in high pressure to form H2SO4. Hydrazine (N2H4) is found to be an ideal compound for removing dissolved oxygen since the products are water and nitrogen gas
N2H4 + O2 = N2 + 2H2o
Mechanical means: It works on Henry's law and Dalton's law. Solubility of gas is directly proportional to pressure. Mechanical desecrator is used
Q. Show properties of the Borax? Salts of boric acids are known as borates. As said earlier, hydrated borates occur naturally, e.g., borax, Na 2 B 6 0 11 . 5H 2 0, kernite, Na
Table gives some halides and oxides of the 3 d series elements, selected to show the range of stable oxidation states. These follow the similar trends as required in aqueous chem
Which of the following orbital is not possible: (1) 3 f (2) 4 f (3)5 f (4) 6 f Ans: 3 f
which quantities are conserved in all oxidation-reduction reactions
which element is the largest size halogen.
effects of ano,alous behaviour of beryllium
The two electrons in K sub-shell will differ in : (1)Principal quantum number (2)Azimuthal quantum number (3)Magnetic quantum number (4)Spin quantum number Ans:Spin
define defination,
The valency of phosphorus in H3 PO 4 is: (1) 2 (2) 5 (3) 4 (4) 1 Ans: 5
Explain the properties of ionic bonding
Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!
whatsapp: +1-415-670-9521
Phone: +1-415-670-9521
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd