Solution of chemistry tasks
|What you need to know to solve chemistry tasksSolution of chemistry tasks 2: How to determine the number of substances for the reactionSolution of chemistry tasks 4: How to determine the shelf life of food products|
| In practice, we sometimes encounter problems associated with determining a quantitative assessment of the substances entering into a chemical reaction, the estimate of the number obtained in this reaction products, substances of interest to us. The hosts certainly often determine the percentage of a substance in solution and how much one or the other substances you have to take. How to calculate the amount of a substance that would be neutralized or neutralized another substance? How much gas will be allocated, if to the citric acid solution add soda? How to cook, for example, a 5% solution of potassium permanganate, and many other tasks encountered in everyday practice.
The purpose of it article Solution of chemistry tasks - to show how you can easily solve these tasks without resorting to complex chemical calculations, and applying only a general knowledge of mathematics and a bit of general knowledge of chemistry.
By the way, what You need to know to solve simple chemistry tasks:
Well, let's look at the most widespread task, how to determine a percentage of a substance in solution and how much you need to take this substance and the solution.
Solution: what % of a substance in solution? Is as pure substances contained in 100 ml of solution. The solution consists of a pure substance and a solvent therefore, 100 ml of the solution will consist of 5 grams of pure substances (vinegar) and 95 ml of solvent (water) it is important to remember!
% = (M substance) / (M solution) х 100.
In the task we have 20% solution of acetic acid. Find the mass of the new solution obtained by adding water to the 20% solution. From the formula we obtain: (M substances) / % x 100, i.e., 20 ml / 5 x 100 = 400 ml. We received 400 ml of a solution containing 20g of pure substances (vinegar), then 400 ml - 20 = 380 ml of water in a new solution. But don't forget, 20% solution contained water, and it was 80 g of water per 100 ml (95 + 5 =100). Therefore, in order to dilute our 20% acetic acid containing 80 ml of water, we need for every 100 ml of 20% of the initial solution add another 380 - 80 =300 ml of pure water.
- if you do not use the formula, you will make a proportion:
The task of the determination of the amount of reaction products or reactants.
Suppose this condition. We need to neutralize the acidic environment. You accidentally poured into 200 ml of hydrochloric acid (HCl), and you have washing soda (Na2CO3) (or its second name - soda ash). Now: how much to take take washing soda to neutralize 200 ml of hydrochloric acid!?
write the chemical reaction of hydrochloric acid with washing soda:
Such chemical task can be a little complicated, given the concentration of acid. In this case, we need to calculate how much of a pure substance is in solution (as in the previous task 1), and then to make a proportion with the amount of hydrochloric acid. But in any case, even if the acid have a lower concentration, then our solution will fulfill the solution because, in this case, the soda will be taken in excess!
Chemistry task 3
But, have You ever read the packaging of the products expiration date products! For sure! There is the date of manufacture and shelf life at a certain temperature. But it is not always possible to store the products at the recommended temperature. Now! You can define shelf life, if you know the conditions recommended storage. So, task in chemistry:
Properties of acids
Getting acids Complex substances. Water hardness
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