Sapling Week 1 #8

[Sean Phen]

"Determine the molecular formula and molecular mass of the compound represented by the chemical structure. Round your answer for the molecular mass to the hundredths place. Lines represent bonds between adjacent atoms."

How do I find the molecular formula and molecular mass of the compound shown in the attached picture? After attempting it many times, this problem still confuses me.

[jasonfarrales3D]

Referring to the picture, count the amount of each element provided in order to find its molecular formula. To give you a hint, there are six Carbons in the compound, so the first part of its molecular formula would be C6. From there, you should be able to find its molecular mass by adding up the total amount of its atomic mass.

[Christine Ma 3L]

Since the compound is shown in the picture, you simply count up all the different atoms shown to find the molecular formula.
There are 6 C's for carbon, 6 O's for oxygen, and 8 H's for hydrogen, so the molecular formula is C6H8O6.

To find the molecular mass of the compound, you use the mass of each individual atom (each carbon atom, each oxygen atom, etc.) and add them all together to find the total mass of the molecule.
The atomic mass of each atom can be found on the periodic table: carbon's is 12.011 amu per atom, hydrogen's is 1.008 amu per atom, and oxygen's is 15.999 amu per atom.
The mass of 6 carbon atoms, 8 hydrogen atoms, and 6 oxygen atoms gives you the mass of the entire molecule, or its molecular mass.
6(12.011) + 8(1.008) + 6 (15.999) = 176.124 amu

Keep in mind the answer should be rounded to the hundredths, so the masses you use for each atom also have to go up to the hundredths (at minimum).

[Sameer Chowdhury 3C]

Something that helped me figure out the molecular formula was drawing it out for myself. Having it on paper made it a lot easier for me to count the number of carbons, oxygens, and hydrogens there were. From there you simply need to multiply the number of each atom by their respective atomic weight and then add the resulting multiplications together.

[Gicelle Rubin 1E]

Hi! I remember when I saw this problem and was completely overwhelmed but it's actually a lot easier than it seems!
To find the molecular formula, simply count how many of each there are for C, H, and O. Upon counting, you'll see you have C6H8O6.

To find the mass of the compound, you have to multiply the atomic mass of each element by how many of that element there are in that compound:
6(12.01) + 8(1.008) + 6(16)
That gives you 176.124 atomic mass units (amu) and those are your answers!
I hope this helped!!

[Gina Spagarino 3G]

Hey, everyone already explained it really well above, and it is a lot easier than it looks at first! Keep in mind that the double bonds in this compound will not effect its mass since the hydrogens were already drawn out (sometimes the H's may not be explicitly shown, but they are here).

[Andrew Yoon 3L]

To find the molecular formula, count the number of carbons, hydrogens, and oxygens, respectively. The order of the elements in the molecular should be CHO. Once you have found the number of each element (C6H8O6), you can find find the molecular mass of the compound. The molar mass of carbon, hydrogen, oxygen is 12.011 amu per atom, 1.008 amu per atom, and 15.999 amu per atom, respectively. For each element, multiply the atomic mass by the number of atoms. For carbon, it would be (12.011 amu/atom) x 6 atoms. For hydrogen, it would be (1.008 amu/atom) x 8 atoms. Finally for oxygen, it would be (15.999 amu/atom) x 6 atoms. Then, you want to add all the amu's to get the finaly molecular mass.

Hope this helps!

[Michelle Magana 2B]

I was stuck on this problem for a while too! At first, I thought the double bonds had a bigger meaning for this problem but they didn't. I counted the elements (from the picture) for the molecular formula and later calculated the molar mass.

[America Alvarado]

I have a follow up question. How would one know if there are double or triple bonds involved? If when writing the molecular formula we don't count the bonds?

[Cooper_Geralds_3B]

Hi, a great starting point for this problem is to start by forming the molecular formula by counting the number of each element seen in the structure! I had to do research to figure that out, but once you have the molecular formula, you can proceed as you would following the normal steps for determining molar mass from molecular formula.

[Lauren Strickland 1B]

This question did confuse me at first as well because I thought the double bonds would have to be taken into account. After adding up how much carbon, hydrogen, and oxygen were in the image I got the answer for the molecular formula. It was more straightforward than it seemed.

[MichaelRaad_1F]

I simply counted the number of atoms in the picture and added all their masses

[Britney Tran IJ]

I also just counted up all of the atoms as presented in the image and used the periodic table and molar masses of each element to find the amu!

[IreneSeo3F]

To find the molecular formula, simply count the number of each element in the picture. After finding the molecular formula, you multiply the number of subscripts to the molar mass of each element and the sum is the molecular mass.

[Kainalu Puu-Robinson]

I have another question about this problem, does the order that you list the elements matter? I know when you add them up the molar masses will both be the same but is C6H8O6 and different from H8C6O6 from a structural standpoint?

[Osiris De LeonR 1g]

Sometimes pictures like this could be a little intimidating so just count each element. And then look up the amount there is of each element from there just look up the “weight” on the periodic table for each one. Since there are 6 carbons you would just look it up carbon and see the weight is 12.011 and multiply that by 6 since there are 6 carbons in the structure. Keep doing that for the rest and then add them all together and get the total mass. I hope this made sense, you got this!

[Savannah Torella 1L]

I know that this picture can look very overwhelming at first, but don't be discouraged. When using the picture, you do not need to pay attention to the different kinds of bonds formed. Whether it is a single bond or a double bond, it does not effect the molecular formula or mass. All you need to do is count the number of carbon, hydrogen, and oxygen present in that order. That should give you C6H8O6. Once you get the molecular formula, just use the periodic table to find the molecular mass, which would be 176.12.

[Victoria_Sauceda_1B]

Taking it step by step is the easiest way. Count every letter and write out your equation and then you look up their atomic masses on the periodic table. Once you have the masses of each element you’ll multiply each mass by the number if letters for each one. All together it should equal your molar mass

[Madeline Marron 1I]

It took me an embarrassingly long time to figure out that I needed to capitalize my letting in order for the computer actually accept my answer.

[Daniela Santana 2L]

To solve this problem count how much of each element there is. You would count how many H's there are, then O's, then C's. Once you have that you just write it out as you would write any molecular formula. With the amount of each element being in subscript next to it. Then you simply find the atomic mass of each element. You can find this on any periodic table. Once you have the atomic mass of H, O and C, simply multiply the mass by the amount of each element there is. Then add them up and you have the molecular mass of the compound.

[205323697]

Molecular mass deals with the sum of the amount of atoms in each element. if there are 8 Hydrogens then you want to multiply the mass of hydrogen by 8 since you have 8 Hydrogen atoms. You do this with all the other elements and at the end you add it all up to get your molecular mass.

[Maryeli Garay 2H]

You would want to first count up all the atoms of each element, in order to get the molecular formula. Once you have this, you can find the molecular mass by looking up the elements on the periodic table. You find each of their atomic masses, then multiply this with how many atoms of the element there are in the molecule. Then, you add these values up. :)

[Navdha Sharma 3J]

The molecular formula can be determined from the figure simply by counting the number of atoms of each element in the compound. For instance, you can figure out that the compound has three elements: C, O, and H. Now just count the number of C, H, and O. That will be your molecular formula: C6H8O6.

Thus, the molecular mass = (12.011*6) + (1.008*8) + (6*15.999)
= 176.124 amu

[Juliana Rosales 1H]

I was super confused with this one as well lol. It took me a while to realize that i just needed to count the Hs and stuff in the picture and use the periodic table to calculate the stuff you need.