Calculating Density of a Dye in PMMA Sample

[Hypnotoad]

I'm trying to figure out the number density (molecules/unit volume) of the dye for a sample of dye doped PMMA. The information I have is that the dye makes up 1% by weight of the mixture used to make the sample. I also have the chemical structure of the dye. I looked up the structure of the PMMA and found it here: http://www.psrc.usm.edu/macrog/pmma.htm , but I don't understand what the brackets around the CH_2-C group signify.

 

[Astronuc]

. . . I don't understand what the brackets around the CH_2-C group signify.

The diagram of the molecule shows the unit molecule or monomer - methyl methacrylate. PMMA, or poly-methyl methacrylate, is a polymerized structure. Presumably, they could not make the brackets large enough in that example.

For the molecular mass, try using MM of methyl methacrylate monomer, which has 2 less hydrogen atoms than the MMA molecule, because in the polymer, these sites bond with other carbon atoms in the adjacent MMA molecules.

 

[thepatientmental]

Calculating the density of a dye in a PMMA sample can be a complex task, but with the information you have provided, it is definitely possible. First, let's break down the information you have:

1. The dye makes up 1% by weight of the mixture used to make the sample.
2. You have the chemical structure of the dye.
3. You have found the structure of PMMA.

To calculate the number density of the dye, we need to know the weight of the dye in the sample and the volume of the sample. Since we know that the dye makes up 1% by weight of the sample, we can use this information to determine the weight of the dye. For example, if you have a 100g sample, then 1% of that would be 1g of dye.

Next, we need to determine the volume of the sample. This can be done by measuring the dimensions of the sample or by using the density of PMMA. The density of PMMA can be found by dividing its mass by its volume. The brackets around the CH2-C group in the structure of PMMA signify a repeating unit, which is important in determining the volume.

Once you have the weight of the dye and the volume of the sample, you can use the formula for density (density = mass/volume) to calculate the density of the dye in the PMMA sample. This will give you the number of molecules of dye per unit volume.

It is also important to note that the chemical structure of the dye and PMMA can provide additional information such as the molar mass and molecular weight, which can be used in more advanced calculations.

I hope this helps in your calculation of the density of the dye in your PMMA sample. Remember to double check your calculations and use accurate measurements to ensure the accuracy of your results.