How do I calculate the relative molecular or relative...?

Question

How do I calculate the relative molecular or relative formula masses of the following:
a) ethanol, C2H5OH
b) oxalic acid dehydrate, H2C2O4.2H2O
c) potassium dichrromate, K2Cr2O7
d) calcium hydroxide, Ca(OH)2
e) silver iodide, AgI

Note: I am asking for help on how to do these questions. What are the processes I must do to calculate these relative molecular or relative formula masses of the above examples? Thanks for helping. I don't mind you showing me how to do a couple of them completely if you don't mind. I'm having trouble with these ones. I do have a large chemistry book but I can't work these ones out. Thanks for helping me.

what is a subscript of an element?

in b: ethanol is C2H5,OH

Is that

C*2, H*6 and O*1? Are the H's added together (H5+H)?

Zn=65.39, doI round it or not until I have the answer and then round the answer? Do I use 65.39+... and then round the answer as a whole or round each of the elements as I add them together? Will I get the answers wrong for rounding the elements? How do oI know If I need to round something what about 140.9 for example? Do I round it to 141?

Answer 1

Look up the mass of each element on the periodic table. Multiply the mass by the subscript of that element in the formula. Add all the masses together for the molecular mass.

Example: Zn(NO3)2

Zn = 65.4 x 1 = 65.4
N = 14.0 x 2 = 28.0
O = 16.0 x 6 = 96.0
mass = 189.4 amu

Answer 2

First, the easiest thing to do is to get the periodic table, then locate the masses os the element wich is usually on top of the element. For
a) ethanol,C2H5OH- (12*2)+(1*6)+(16*1)= 24+6+16+1=46
b) oxalic acid dehydrate,H2C2O4.2H2O: (1*6)+(12*2)+(16*6)=126
c)potassium dichromate,K2Cr2O7: (39.1*2)+(52*2)+(16*7)=294.2
d)calcium hydroxide,Ca(OH)2: (40.1*1)+(16*2)+(1*2)=74.1
e)silver iodide,AgI: (108*1)+(127*1)=235
All you have to do is use the molar masses to multiply the total number of elements present.

Answer 3

If I understand your question wisely, that's greater of a math question. If one molecule of hemoglobin is 33% Fe, then you are able to set variables to clean up, on condition that a million iron atom weighs 55.87 g/mol If each and every molecule of hemoglobin has 2 Iron atoms, it particularly is (55.87 x 2) = 111.74g in line with ONE 0.33 of hemoglobin. Multiply that extensive kind by using 3 and that's greater or less the respond. ANS: 335.22 g/mol hemoglobin

Answer 4

did u mean that molar mass of each?
if u mean molar mass..
for a, you have 2 carbons, 6 hydrogen and 1 oxygen
just add masses but u need to mutiply how many atoms of each & its mass.. for C (2* 12.01) + for H (1.008 *6 ) + for O (1* 16)
molar mass mean how many gram in 1 mole of C2H5OH
So you mutiply and add them together. you will get 46.068g

for b, you have 6 hydrogens, 2 C, 6 O
so you will get126g
for c, 294.2 g
for d, 38.08g
for e, 234.8 g

hope that would help you!