[rachellemamauag]

1)NaOH + CaBr2 -->



Will this reaction occur? ____



2)Pb(NO3)2 + HCl -->



Will this reaction occur? ____



3)Na2CO3 + KF -->



Will this reaction occur? ____



4)AgNO3 + CuSO4 -->



Will this reaction occur? ____



5)AgF + NiCl2 -->



Will this reaction occur? ____

[Unknown008]

Could you please try answering the answers yourself? For example, if you say 'no' for number one, you say then why you think there will not be any reaction. Please. We are not supposed to do your work, but help you with them. We therefore expect a certain minimum from you. :)

[rachellemamauag]

OK.. thanks.. but how will I answer this one:

for the equation 2AgNO3 + K2CrO4 ---> Ag2CrO4 + 2KNO3, how much of each reagent that is required to make 100 grams of silver chromate

...

[Unknown008]

Good, you have the balanced equation. Find the Mr of silver chromate.

Then, work out the number of moles in that mass.
1 mole of silver chromate has a mass equal to its Mr.

You also have the mole ratio through the equation. For each reagent, therefore, find their Mr, and multiply them by their corresponding number of moles.

Hope it helped! :)

Post your answer, to see if you got it right.

[rachellemamauag]

What's Mr?

I'm confused..

[Unknown008]

is relative molecular mass or relative formula mass.

Add the (or relative atomic mass) of the elements present in the compound to get the Mr.

For example, hydrogen has a mass of 1. However, the hydrogen molecule, consisting of 2 H atoms is 1+1= 2. The hydrogen molecule therefore has a relative molecular mass of 2.

1 mole of hydrogen atom has a mass of 1g
1 mole of hydrogen molecule has a mass of 2g.

Does that help?

[rachellemamauag]

Hi.. can I ask how to answer this one

How many moles of H2O are formed if .46 mol of NH4NO3 is used in the reaction

[Unknown008]

Hmm, which reaction?

[rachellemamauag]

Oh sorry, this reaction:

NH4NO3 -----> N2O + 2H2O

[Unknown008]

That's OK :D lol

Ok, it seems to me that you're new to these things. Were you able to do the problems you originally posted?

And for this one, here's the reaction, which I retyped:



Ok, do you see there's only one NH4NO3, only one N2O and two H2O?

Well, that means that one mole of NH4NO3 gives one mole of N2O and two moles of water.

By proportion, 2 moles of NH4NO3 give s 2 moles of N2O and 4 moles of H2O.

Similarly, 0.46 mole of NH4NO3 will give 0.46 mole of N2O and (2 x 0.46) mole of H2O. That makes 0.92 mole of H2O.

You think you can do other problems of the same type as this one? :) Don't hesitate to ask if you're not sure, OK? :)

[rachellemamauag]

I got it thanks a lot!

For this one:
Given: 1.525 grams - mass of compound N & O
0.712 grams of N and required is the empirical formula of the compound

I solved for the mole of N which is 0.05 mol.. what is the next step?will I subtract it from 1.525 which is the mass of the compound?

[Unknown008]

I guess you mean subtract the mass of nitrogen from the total mass, yes. You'll have 1.525 - 0.712 = 0.813. With that, find the number of moles of oxygen. Good job! :)

[rachellemamauag]

Thanks again.. I am confused if when shall I use the avogadro's number.

[Unknown008]

Ok, you got the number of moles of both, right?

N : 0.05
O : 0.05

right?

Divide by the smallest number of them, it's 0.05. You'll have:

N:1
O:1

Therefore, the empirical formula is

The avogadro's constant is something separate.

In 1 mole of something contains the avogadro's number.

Ok, say, I have one mole of nuts, that means I have nuts.

If there's one mole of oxygen atoms, that means there's oxygen atoms.

If you have one mole of oxygen molecules, you have oxygen molecules.

However, since in one molecule of oxygen you have two oxygen atoms, you'll have twice , that is atoms on oxygen.

[rachellemamauag]

Yes I got the answer NO.. I just asked about avogadro's no. because I'm just quite confused..
By the way,we will have a long examination about naming compounds, can you give me some advice on it.

[Unknown008]

Hm...

You should know that everything salt containing :

is called sulphate (now as sulfate)

is called nitrate

is called phosphate

every substance bonded with oxygen is called 'oxide', or sometimes dioxide like in CO2, carbon dioxide, and NO2, nitrogen dioxide, SO2, sulfur dioxide... or monoxide in the case of CO, carbon monoxide and NO nitrogen monoxide.

For substances with a non-metal attached to them, the non metal ends with -ide.

You have NaCl - Sodium Chloride
Na2S - Sodium Sulfide

Then, you have the -ites, similar to those I mentioned above, but with one less oxygen (I don't think you have to know that one though):

is called sulfite

is called nitrite

is called phosphite

[rachellemamauag]

Hello!I just want to ask this one for my assurance.. In a polar covalent bond, Does electron cloud shifted more toward one of the atoms?thanks.

[Unknown008]

For you to know to which atom the electrons shift to, you have to know about electronegativity. It's strange for me that you are asking about this when you were asking about much simpler things some time before...

Well, anyway, you have to know that oxygen is a more electronegative atom, and electronegative atoms 'like electrons' and so pull them towards them. As a result, the electron cloud would shift towards the oxygen atom in a water molecule.

It is that what creates the polarity. The oxygen atom having more electrons become slightly more negative, and hence gets a delta negative () charge while the hydrogen atoms get a delta positive charge (). The pole of the positive charge is at the centre of the two hydrogen atoms.