Get ready...

Are you all familiar with the stuff? Any queries? doubts? No isn't it. if so just think of the best replay for these question.

what are the products formed if any, at the anode and the cathode, when CuSO4(aq) is being electrolyzed using copper electrodes? Give half-equations.

state the products formed when concentrated aq.CaCl2 is being electrolyzed using inert electrodes. what will happen to the amount of the product formed at the anode if you use an active electrode such as iron in the anode?

How to work out a limiting reagent question..

Limiting reagent calculations are not much more difficult than any other calculations, there is just one step more - comparison of amounts of reacting substances.

Once we have balanced reaction equation we know what amounts of substances will react. Let's try the following reaction of calcium hydroxide synthesis:

CaO + H2O -> Ca(OH)2

One mole of calcium oxide reacts with one mole of water to produce one mole of calcium hydroxide. What will happen if we have one mole of calcium oxide and two moles of water? Well, nothing will change - still only one mole of CaO can react with H2O, so after the reaction there will be one mole of water left. We call the reagent that reacts to the end limiting reagent.

Let's try to find out how much calcium hydroxide will be produced when 10.00 g of calcium oxide reacts with 3.00 g of water.

First of all we have to check which one is limiting reagent. How much water will react with 10.0 grams of CaO?
CaO + H2O -> Ca(OH)2

56.08 g : 18.01 g

10.00 g : x g


56.08 g : 18.01 g = 10.0 g : x g

x = 10.00 g/56.08 g×18.01 g = 3.213 g

We have not enough water - 3.00 g only, when CaO needs 3.213 g, so water is a limiting reagent. How much calcium hydroxide will be produced from 3.00 g of water?


CaO + H2O -> Ca(OH)2

18.01 g : 74.09 g

3.00 g : x g


18.01 g : 74.09 g = 3.00 g : x g

x = 3.00 g/18.01 g×74.09 g = 12.34 g

That's the final answer.

Limiting reagent: answers

answer 1.(a)
NH4NO3=80, Na3PO4=164, (NH4)3PO4=149 [These are relative molecular mass]

NH4NO3 Na3PO4
3 : 1

(3x80)g : 164g
30g : x
x= 20.5g this value is lesser than 50g of Na3PO4 given in the question.it means NH4NO3 is in excess and Na3PO4 is the limiting reagent.

try out the answers for (b) and (c)

Molarity Exercise

For the questions on this worksheet, consider the following equation:

Ca(OH)2(s) + 2 HCl(aq)  CaCl2(aq) + 2 H2O(l)


1) What type of chemical reaction is taking place? _____________________

2) How many liters of 0.100 M HCl would be required to react completely with 5.00 grams of calcium hydroxide?








3) If I combined 15.0 grams of calcium hydroxide with 75.0 mL of 0.500 M HCl, how many grams of calcium chloride would be formed?













4) What is the limiting reagent from the reaction in problem #3? __________

5) How many grams of the excess reagent will be left over after the reaction in problem 3 is complete?

[note 1000cm3 = 1 Liter

Limiting Reagent Worksheet

For the following reactions, find the following:

a) Which of the reagents is the limiting reagent?
b) What is the maximum amount of each product that can be formed?
c) How much of the other reagent is left over after the reaction is complete?

1) Consider the following reaction:

3 NH4NO3 + Na3PO4  (NH4)3PO4 + 3 NaNO3

Answer the questions above, assuming we started with 30 grams of ammonium nitrate and 50 grams of sodium phosphate.

2) Consider the following reaction:

3 CaCO3 + 2 FePO4  Ca3(PO4)2 + Fe2(CO3)3

Answer the questions at the top of this sheet, assuming we start with 100 grams of calcium carbonate and 45 grams of iron (III) phosphate.

Test for nitrate ion

test for carbonate ion

Redox Titration: observe the colour change..

Why e-mail chemistry is not enough

By Ami Angelowicz,www.cnn.com
I heart words and communication. This includes e-mails, text messages, Gchat, BlackBerry Messenger, iChat -- the works. I am a sucker for a well-crafted e-mail or a witty text message. My motto: The way to my heart is through my brain.

That's why I thought Joe could be Mr. Perfect for me. Joe and I met one night at a work gala. I had already put away an entire bottle of wine when I almost knocked him over on the dance floor.

"Do you like to dance, beautiful girl who almost stepped on my foot?" he asked.

"Only when I'm drunk. When I'm sober, I dance like Elaine from 'Seinfeld,' " I replied.

It was a rainy October night and Joe offered to escort me to the subway when the event ended, impressed that I could: a) still walk and b) do it in 3-inch heels. "E-mail me," I slurred, handing him my business card, "I loooove e-mails."

The next day at work, the misery of my hangover was interrupted when Joe sent me a long, witty, intellectually stimulating e-mail, complete with references to popular culture, long words spelled properly (so hot), anecdotes about his life, and plenty of questions about mine. Wait ... what did he look like again?

The e-mails continued, getting more and more opus-like. He responded quickly -- my number-one turn-on. Enough with that "hard-to-get" crap.

Within a few days, he began sending me funny, random text messages along with the novella-esque e-mails:

I just passed the subway stop I walked you to the night we met. Good thing you didn't incapacitate me by stepping on my foot. I want to see you dance like Elaine.

What's your favorite kind of cupcake?

I just saw a man wearing a horse costume on Columbus. Ah ... New York.

He even played along when a week later I told him that I was putting a ban on our e-mail communication because I wasn't getting any work done. In response, he sent a handwritten letter to my office via courier asking me out for Saturday night. I was so overcome that I think I might have peed my pants. It was like this guy could read my mind. Finally, I would get to see him in person again!

That Saturday night I walked into the fancy seafood restaurant ready to pick up our witty repartee right where it left off. As soon as we sat down across from each other, I felt my stomach drop. Something was very, very wrong. He was attractive enough, but I wasn't attracted to him. Why? We had nothing to say to each other. I mean ... nothing. How could this have happened?

What Joe and I had was something I like to call "E(mail)Chemistry" or "EChem" -- really hot technological chemistry. When you've got great EChem with someone, it can often be indicative of real chemistry, but sometimes, sadly, it is not. Why? My theory: E-mails, texts, Gchat, etc. all allow a person to develop what I've dubbed an "EPersona," i.e., their technological way of being.

The tricky thing is that an EPersona may or may not have anything to do with a person's authentic self. The safe distance that technology creates allows people the opportunity to represent their best, most wonderful, sometimes even fantasy self. When you can be calculated, deliberate and thoughtful about every word, you can feel brave enough, safe enough, in control enough to do, say and be things that you could never do, say or be face-to-face.

But the catch is that is the only person you can fall in love with is a real, authentic person -- in person -- not a freaking avatar. And falling in love is about vulnerability, imperfection, and spontaneity.

What I learned from Joe and others like him (sadly, there have been too many) is that amazing EChem is just not enough. Getting to know someone's EPersona is not sufficient. No e-mail (no matter the length) or text message (no matter the wit) can replace that odd, quirky, unpredictable genius that is real/live chemistry between real/live people. That strange electric moment when someone kisses you for the first time and you feel an army of hummingbirds in the pit of your stomach.

A few weeks after the Joe incident, I got set up on a blind date with Adam. We exchanged e-mails before we ever met in person. He didn't respond very quickly, there were no long words in his email.

He misspelled many of the simple words, his grammar was iffy, he didn't catch my reference to "The Fountainhead," and he didn't send me a text message to confirm our date. In fact, I was pretty sure we had nothing in common based on our dull EChem.

Iron lady's brain is rusting!

Former British Prime Minister Margaret Thatcher has dementia.She is famous as the iron lady.

In her forthcoming book,Carol Thatcher reveals that her mother's mental faculties have been in decline for the past 7 years as follows:

"When she learned Latin at school, she absorbed the vocabulary and declensions with her blotting-paper brain. It was a skill honed to perfection during her chemistry degree at Oxford, when scientific equations added yet another dimension to an already orderly mind ...
Whereas previously you would never have had to say anything to her twice, because she'd already filed it away in her formidable memory bank, Mum started asking the same questions over and over again, unaware she was doing so.

It might be something innocuous - such as 'What time is my car coming?' or 'When am I going to the hairdresser?' - but the fact she needed to repeat them opened a new and frightening chapter in our lives."

revision worksheet

TheThermite reaction

Presentation on Reactivity series

Reactivity Series of Metals

The Halogens

We are the Noble Gases

Reactions of alkali metals with cold water