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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: 2 Amigos on September 24, 2007, 06:47:39 PM

Title: Need Chemistry homework help
Post by: 2 Amigos on September 24, 2007, 06:47:39 PM
Hey there guys, I have this huge assignment for chemistry (47 questions) and I am having trouble with these few. Can anyone help?

What is the mass in grams of 5.9 mol C8H18? (C=12.0amu; H=1.01 amu)
 
What is the number of moles in 432g Ba(NO3)2? (BA=137.3amu; N=14amu; 0=16amu)
 
What is the percent composition of Chromium in BaCrO4?
 
What is the empirical formula of a substance that is 53.5%C, 15.5%H, 31.1%N by weight? (C=12amu; H=1.01amu; N=14amu)
 
If .89g K and 1.18g Cr react with 1.27g O, what is the empirical formula of the compound? (Molar Masses: K=31.1g; Cr=52G; 0=16g)
 
Correct name of CoCI2?
 
When naming a transition metal ion that can have more than one common ionic charge, the numerical value of the charge is indicated by a ______?
 
Molecular compounds are usually _____?
 
In Cu2O, the charge of the copper ion is____?
 
Sodium Nitrade symbol?
 
Which element combined with fluorine would make an ionic compound?
 
Pottasium Sulfide symbol?
Title: Re: Need Chemistry homework help
Post by: AWK on September 25, 2007, 01:47:24 AM
Quote
What is the mass in grams of 5.9 mol C8H18? (C=12.0amu; H=1.01 amu)
 
What is the number of moles in 432g Ba(NO3)2? (BA=137.3amu; N=14amu; 0=16amu)
 
What is the percent composition of Chromium in BaCrO4?

You should start from calculatiom of molecular mass

Quote
What is the empirical formula of a substance that is 53.5%C, 15.5%H, 31.1%N by weight? (C=12amu; H=1.01amu; N=14amu)
 
If .89g K and 1.18g Cr react with 1.27g O, what is the empirical formula of the compound? (Molar Masses: K=31.1g; Cr=52G; 0=16g)

Change masses (percent is a mass in 100 g of compound) to moles of elements, then then find a common multiplier that gives the  lowest integer numbers for  moles of elements

Title: Re: Need Chemistry homework help
Post by: Sev on September 25, 2007, 04:21:50 AM
Quote
When naming a transition metal ion that can have more than one common ionic charge, the numerical value of the charge is indicated by a ______?

Roman numeral

Quote
Molecular compounds are usually _____?

Covalent

Quote
In Cu2O, the charge of the copper ion is____?

Hint: Oxide is 2-, Cu2O is electrically neutral.