Nagranie audio prezentujące tematykę zmian stężenia roztworów.
What is the name of the process in which we add solvent to the solution?
During many activities related to work, research or everyday life, we add water or other solvent to various liquids (substance solutions). The process that we then cause is called dilutionsolution dilutiondilution. As a result, we increase the amount (mass) of the solvent, whereas the amount (mass) of the solute does not change. What happens with the concentration percentage of the diluted solution?
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Ilustracja przedstawia lekarkę, która przygotowuje lek do wstrzykiwań, dodając do substancji czynnej rozpuszczalnik obojętny dla organizmu.
The doctor or nurse often prepares the medicine for injection by adding a solvent that is inert to the body to the active substance solution
How does the concentration of the solution change after dilution?
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Ilustracja przedstawia model procesu rozcieńczania roztworu. U góry znajduje się zlewka z wodą oraz zbliżenie lupy na cząsteczki wody. W środkowej części znajduję się strzałka prowadząca w dół oraz rysunek przedstawiająca dolewanie wody z jednej zlewki do drugiej. Dolna cześć ilustracji przedstawia zlewkę z większa ilością wody oraz lupę przybliżającą widok cząsteczek wody. Po rozcieńczeniu w wodzie jest mniej cząsteczek.
The model of the solution dilution process
When adding a further portion of solvent to the solution, the number of solvent particles per diluted solute particles increases. Thus, the mass of solvent relative to the mass of solute increases.
Another possible way to dilute the solution is removing the solute.
This treatment is quite difficult to make and is only possible with concentrated solutions.
It consists of cooling the solution to a temperature at which solubility of the solute is low enough that the substance is released from the solution. After removal of the separated substance, the solution contains less of it and its percentage is lower than the original one.
Task 1
Watch an presentation ‘Steps to resolve the task’. Pay attention to the methods of calculating the concentration percentage when diluting the solution by adding water.
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Ilustracja przedstawia tytuł prezentacji: Etapy rozwiązywania zadania do obliczenia. Ilustracja zawiera anglojęzyczna napisy : stage of solving the task to calculate percentage concentration when diluting the solution by adding water.
How to calculate the change in solution concentration? Let's check the example.
Source: GroMar Sp. z o.o., licencja: CC BY-SA 3.0.
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Ilustracja przedstawia kolby miarowe i zlewki. 30 gramów wody zostało dodane do 70 gramów 25% roztworu kwasu chlorowodorowego.
30 grams of water were added into 70 grams of a 25% hydrochloric acid solution. What is the percentage concentration of the solution obtained?
Source: GroMar Sp. z o.o., licencja: CC BY-SA 3.0.
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Ilustracja przedstawia dane wartości: (Mw - masę wody, która wynosi 30 g, Mr1- masę roztworu, która wynosi 70 gramów oraz Cp1- procentowe stężenie wynoszące 25 %) oraz szukane wartości - Cp2 - procentowe stężenie.
We are writing out data and searched based on the content of the task.
Source: GroMar Sp. z o.o., licencja: CC BY-SA 3.0.
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Ilustracja przedstawia wzór na obliczenie stężenia - Ms (masę substancji) pomnożone przez 100% i podzielone przez Mr- masę substancji rozpuszczonej. Poniżej znajduje się przekształcony wzór- Ms wynosi stosunek pomnożonych Cp1 i Mr1 do 100%. Ms- masa substancji wynosi 25% pomnożone przez 70 gramów i podzielone przez 100%. Otrzymany wynik to 17,5 grama.
Let's use the formula, transform it and substitute our data into it. We calculate the mass of the substance contained in 25-percent solution - the first solution.
Source: GroMar Sp. z o.o., licencja: CC BY-SA 3.0.
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Ilustracja przedstawia dalsze kalkulacje. Mr2- masa drugiej substancji rozpuszczonej to suma Mr1- masy substancji 1 oraz Mw - masy wody. To oznacza, że 70 gramów dodajemy do 30 gramówi otrzymujemy wynik 100 gramów.
Now we are calculating the mass of the solution after adding water, i.e. the mass of the second solution - after dilution.
Source: GroMar Sp. z o.o., licencja: CC BY-SA 3.0.
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Cp2 czyli stężenie roztworu drugiej substancji to stosunek Ms- masy substancji do Mr2- masy substancji rozpuszczonej 2 pomnożonej przez 100%. W wartościach liczbowych będzie to 17,5 grama podzielone przez 100 gramów i pomnożone razy 100%. Otrzymujemy wynik 17,5 %.
Knowing the mass of the substance calculated from the first solution and the mass of the solution after dilution, we calculate the percentage concentration of the solution after dilution (after adding water). The concentration of the newly obtained solution is 17.5%.
Source: GroMar Sp. z o.o., licencja: CC BY-SA 3.0.
Calculate the percentage concentration of sugar in the drink that was created by adding 200 cmIndeks górny 33 water (with a density of ) to 20 g juice with sugar concentration 50%. Give the result to one decimal place.
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Wykonaj ćwiczenie zgodnie z poleceniem.
Wykonaj ćwiczenie zgodnie z poleceniem.
Exercise 2
Calculate how much water should be added to 30 g of 6% saline solution to make a 3% solution.
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Wykonaj ćwiczenie zgodnie z poleceniem.
Wykonaj ćwiczenie zgodnie z poleceniem.
Exercise 3
During throat infection, it is recommended to rinse it with a diluted solution of hydrogen peroxide, i.e. a 3% solution of hydrogen peroxide. The rinsing solution is obtained by diluting the hydrogen peroxide in a volume ratio of 1 : 50. Calculate, with an accuracy of one thousandth of a percent, the concentration of hydrogen peroxide solution after dilution. Assume that the density of hydrogen peroxide and ordinary water is equal
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Wykonaj ćwiczenie zgodnie z poleceniem.
Wykonaj ćwiczenie zgodnie z poleceniem.
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Exercise 4
Indicate activities whose performance will reduce the percentage concentration value of a given solution. Możliwe odpowiedzi: 1. evaporation of the solvent, 2. addition of the solvent, 3. addition of the substance, 4. addition of a solution with lower concentration, 5. addition of a solution with higher concentration
Indicate activities whose performance will reduce the percentage concentration value of a given solution. Możliwe odpowiedzi: 1. evaporation of the solvent, 2. addition of the solvent, 3. addition of the substance, 4. addition of a solution with lower concentration, 5. addition of a solution with higher concentration
Indicate activities whose performance will reduce the percentage concentration value of a given solution.
evaporation of the solvent
addition of the solvent
addition of the substance
addition of a solution with lower concentration
addition of a solution with higher concentration
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Prepare for your friend a task to calculate the change in the solution concentration. Give four answers, including correct ones.
Prepare for your friend a task to calculate the change in the solution concentration. Give four answers, including correct ones.
Prepare for your friend a task to calculate the change in the solution concentration. Give four answers, including correct ones.
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Summary
Concentration of the solution can be changed by dilution.
As a result of dilution, the concentration of the solution decreases.
The solution can be diluted by adding a solvent to it.
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Tablica interaktywna. How was this lesson? Did you like it? Finish selected sentences. Propozycje 1.It was easy for me..(uzupełnij)., 2.It was difficult for me..(uzupełnij)., 3.Today I learned..(uzupełnij).,4. I understood that..(uzupełnij)., 5.It surprised me.(uzupełnij).
Tablica interaktywna. How was this lesson? Did you like it? Finish selected sentences. Propozycje 1.It was easy for me..(uzupełnij)., 2.It was difficult for me..(uzupełnij)., 3.Today I learned..(uzupełnij).,4. I understood that..(uzupełnij)., 5.It surprised me.(uzupełnij).
Source: GroMar Sp. z o.o., licencja: CC BY-SA 3.0.
Homework
Task 2.1
The carer was preparing the medicine for a patient. On the ampoule with the drug it was written: 10 ml of an 8‑percent solution of the active substance. According to the recipe, the ampoule content should be mixed with 90 ml of water, mixed thoroughly and administered 3 times a day at 5 ml per dose. Inadvertently, the carer added 110 ml of water. Calculate the volume of the drug solution she should now give to the patient to give him the right dose of medicine.
Keywords
solution concentration percentage, concentration change, solution, solvent, dilution of the solution
