LABORATORY WORK No 3

Performed by:

Ruzena Zakova, Marie Horka

Conditions:

t = 19.0 °C; p = 1005.5 hPa; φ  = 42.0 %

Topic:

Filtration of Soup

Tasks:

1.

Separate the ingredients of soup through filtration.

2.

Determine the mass fraction of solid part in the soup.

3.

Rate the efficience and velocity of separate filtrations.

Theory:

Substances in our surroundings can be divided in chemically pure substances and mixtures. The properties of substances depend on their ingredients, on the sizes of the separate parts of the mixtures and on their mutual allocation.

The separate parts of a mixture can be divided by using various methods. For instance separating two liquids that differ from each other by boiling temperature is called distillation. Separating a solid substance (rough crystals or particles of solid amorphous matters) from liquids or gases is called filtration. The nature of a filter is the filter material (paper, fabrics, asbestos, siliceous earth etc.), that is chosen according to the size of particles. During the passage of a mixture of liquid and solid substance through the filter, the liquid seeps through the filter (it is called filtrate) and the solid substance remains on the filter.

Aids:

Packet soup, magnifying glass, filtering funnels, various filters, beakers, kitchen scales, Petri dish.

Procedure:

1.

Determine the mass m₁ [g] of soup mixture from the label of the instant goulash soup bag.

2.

Observe the ingredients of the solid mixture by means of the magnifying glass and try to determine the kind of separate components.

3.

Dissolve the soup mixture in the half of recommended amount of cold water, i. e. in 500 ml water, in a larger beaker (m₂  = 500 g).

4.

Observe which soup particles are soluable in the water and which, on the contrary, insoluable. A dissimilar (heterogenous) mixture developes, that is called suspension (solid substance is dispersed in liquid). After stirring the mixture properly divide it into 7 identical parts.

5.

Prepare 6 filter equipments that differ only in the kind of filter. Put the folded filter paper into the 1. filtering funnel, the folded newspaper paper into the 2. one, a roll of cotton wool into the 3. one, linen into the 4. one, very fine sand into the 5. one and rough sand (0-4 mm) into the 6. one. Prepare metal tea-strainer for the 7. part of the soup.

6.

Filter the goulash soup gradually through 7 different filters. Notice the speed and effectiveness of various kinds of filtrations.

7.

Pour the solid ingredients of soup from all filters into the Petri dish, dry them and determine their mass m₃ [g] on the scales.

8.

Computete the mass fraction w_A from the original whole instant soup straight from the bag in the soup according to the formula w_A = m₁ : (m₁+m₂)

9.

Compute the mass fraction w_B of the solid in water insoluable part in the original soup mixture in the bag according to the formula w_B = m₃ : m₁

10.

Compute the mass fraction w_C of the solid in water insoluable part in the soup according to the formula w_C = m₃ : (m₁+m₂)

Picture:

a)

packing of the goulash soup bag

b)

filtration of goulash soup suspension

Measuring:

1.

The mass of the original dry goulash mixture in the bag:

m₁ = 120 g

2.

The mass of the prepared suspension of the goulash soup:

m₁ = 120 g, m₂ = 500 g; m₁ + m₂ = 120 g + 500 g = 620 g

3.

The mass of the solid in water insoluable component of goulash mixture:

m₃ = 95 g

Computation:

1.

The mass fraction w_A  of the original dry soup mixture in the whole suspension of goulash soup:

w_A = m₁ : (m₁+m₂) = 120 : 620 = 0.194 = 19.4 %

2.

The mass fraction w_B of the solid (in water insoluable) part in the original dry soup mixture in the bag:

w_B = m₃ : m₁ = 95 : 120 = 0.792 = 79.2 %

3.

The mass fraction w_C of the solid component in the ready soup:

w_C = m₃ : (m₁+m₂) = 95 : 620 = 0.153 = 15.3 %

Conclusion:

1.

The filtration on sand filters went fastest of all, and the sand separated also the finer solid components from the soup suspension.

As for the colours, the clearest filtrate was obtained by using the cotton wool and several times folded linen. The filter paper filtered slowest of all. The newspaper paper turned out to be a failure as a filter.

2.

The original soup mixture from the bag makes up 19.4 % of the soup. The in water insoluable part of soup mixture makes up 79.2 % of the whole dry soup mixture in the bag and 15.3 % in the ready soup.