Chemistry, 14.04.2020 23:36, ezy53

To determine the purity of a sample of Na2HPO4, a 2.469-g sample is dissolved and diluted to volume in a 100-mL volumetric flask. Analysis of the resulting solution gives an absorbance of 0.135. What is the purity of the Na2HPO4

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answered: Rakeem458

Question: The question is incomplete. below is the calibrated data of the question and the answer.

ppm Absorbance

2130 0.048

4260 0.110

6400 0.173

8530 0.230

% purity = 95.32

Explanation:

NOW MOLAR MASS OF Na2HPO4 =141.96

ATOMIC MASS OF PHOSPOROUS=30.974

141.96/30.974 =4.583 g

If 4.583g of Na2HPO4 is added in 1000 ml volumetric flask and make the volume to 1L with water, you will get 1000 ppm P solution

Therefore, 2.469g in 100 mL =5387.300 PPM

Calculating the percentage error, we have

%ERROR=(5387.300-5146.118)/5146.118 *100

=4.68

SO %PURITY = 100-4.68 =95.32

To determine the purity of a sample of Na2HPO4, a 2.469-g sample is dissolved and diluted to volume

answered: Guest

it can be observed without changing the identity of the object.

it depends on what substance you're talking about as well as many other factors. in quantum mechanics, the observation of particles affects the observers ability to measure certain properties. for example: you can know the velocity of a particle, but you can't know it's position; or you can know it's position, but not it's velocity. it's like trying to find out where a grain of sand is by throwing other grains of sand at it. once you find out where it is, it's been moved. it's also like trying to find an answer to the question of whether or not a tree falling in a forest makes a sound if nobody is there to hear it. paradoxically, the only way to find out is to be there and hear it.

answered: Guest

The answer to your question really depends on three things: how much water you have, how cold it is to start out, and how cold the things around it are. water actually freezes when it gets to 32 degrees fahrenheit (0 degrees celsius), but the time it takes to get there may be different. let's start with the first. if you take two glasses, and fill one with a tiny bit of water, and the other about halfway, then put them both in the freezer, the one with less water will freeze first (you can try this at home, but i recommend using plastic cups and not glass ones). now let's move on to the second part. let's say you have two glasses, and you fill one with really cold water that has been in the refrigerator, and the other with really hot water from the sink. if you put both of them in the freezer, the one that started out colder will freeze first. for the third part, let's imagine that you have two glasses with the same amount of water in them, and the water is at the same temperature. imagine putting one outside on a really really cold day in georgia, and having a friend in alaska put one outside on the same day. since it would be so much colder in alaska, the glass of water there would freeze before yours. so, if you took a tiny bit of really cold water in a glass, and put it outside on a cold day in alaska, it would freeze a lot faster than a big glass of hot water outside on a cold day in georgia.

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To determine the purity of a sample of Na2HPO4, a 2.469-g sample is dissolved and diluted to volume...