PREDICT
RENDEMENT OF PRODUCT A REACTION
In chemistry, the chemical yield, the yield of
the reaction, or only the rendement refers to the amount of reaction product
produced in the chemical reaction. Absolute rendement can be written as weight
in grams or in moles (molar yield). The relative yield used as a calculation of
the effectiveness of the procedure is calculated by dividing the amount of
product obtained in moles by the theoretical yield in moles:
To obtain a percentage yield, multiply the
fractional yield by 100%. One or more reactants in chemical reactions are often
used redundantly. The theoretical rendement is calculated based on the number
of moles of the limiting reagent. For this calculation, it is usually assumed there
is only one reaction involved. The ideal chemical yield value (theoretical
rendement) is 100%, a value highly unlikely to be achieved in its practice.
Calculate the percent of rendemen that is by using the following equations
percent rendemen = weight yield / weight of yield divided by the sample weight
multiplied by 100%
Example:
1. STOIKIOMETRI
If the reaction between 6.0 grams of ethane, C2H6 ¬ (Mr = 30) with 7.1 grams of Cl2 (Mr = 71) yields 5.16 grams of C2H5Cl (Mr. 64.5), the percentage of ethyl chloride rendement is ....Discussion:
C2H6 + Cl2 → C2H5Cl + HCl
C2H6 = 6/30 = 0.2 mol
Cl2 = 7.1 / 71 = 0.1 mol (discharged)
C2H5Cl (theoretical) = 1/1 x 0.1 mol = 0.1 mol
= 0.1 x 64.5 g = 6.45 g
% Rendemen = 5.16 / 6.45 x 100% = 80%.
2. COPPER SYNTHESIS (II) PENTAHIDRAT SULFATE OF
COPPER WIRE
Porpuse:
1. Knowing the technique of making copper (II) sulfate.
2. Calculate% rendement of copper (II) sulfate crystals.
Data analysis:
Early copper wire weight = 7.0044 grams
Weight of filter paper = 0.9608 gr
The weight of filter paper + crystal = 19.2921 gr Mr. Cu = 63.5 gr / mol
Mr. CuSO4.H2O = 249.5 gr / mol
CuSO4.5H2O = crystalline mass (weight of filter paper + crystal) - weight of filter paper
= 19.2921 - 0.9608
= 18.3313 grams
Mol Cu = gr / Mr = 7,0044 / 63,5 = 0.11 mol The mass of CuSO4.5H2O
theoretically = M × Mr.
= 0.11 × 249.5
= 27.445 gr
= 18,3313 / 27,445 × 100
= 66.79%
This experiment is aimed to know the technique of making CuSO4.5H2O, where
the material used isaquadest(H₂O),concentratednitric acid (HNO₃),
concentratedsulfuricacid (H₂SO₄),filter paper and copper wire (Cu), 30 mL water
into a beaker glass, then mixinga concentrated H₂SOlarsolution of 11.9 mL.It is intended that there is no explosion due todilutionof concentrated sulfuric acid with water to produce exothermic exhaledheatbecause the attractiveness of sulfuric acid to water is very strong, where thereaction occurs:
H₂SO₄ (aq) + H₂O (l) → H₃O (aq) + HSO₄ˉ (aq).
Then add 7 grams of copperwire to the solution, the sulfuric acid will not make
the copper powderdissolve but the sulfuric acid solution serves to create an acidic
atmosphere and form sulfate groups in copper until copper sulphate is formed so
that to dissolve the copper wire is added 17 , 5 ml of concentrated nitric acid,
because copper can be oxidized and dissolved in concentrated nitric acid so
that there will be a reaction:
3Cu (s) + 8HNO ₃ (aq) → 3Cu (NO3) 2 (aq) + 2NO (g) + 4H2O (l)
If the three solutions are mixed then will release NO gas that is not colored, but in this experiment
the resulting gas is brown, this is because because NO gas is very reactive to oxygen to form brown
NO2 gas, there is sediment and smoky so that the reaction will be formed :
2NO (g) + O2 (g) → 2NO2 (g)After that heated until the brown gas is not out again, where the
heating is to accelerate the reaction, then boil the solution until the crystal is formed. From the
heating process is done, formed a dark blue solution. To separate the filtrate with the sediment
(impurities) then penyarinngan made. The filtration process is not carried out when the solution
is cold, but at the time the solution is still hot. The purpose is that the desired crystal formation
is desired (the impurity-free crystal) can be avoided. The filtered filtrate is cooled in the acid
cabinet to form a copper (II) sulfate crystal. The same reaction equation is:
Cu (NO3) 2 + H2SO4→ CuSO4 + 2HNO3
CuSO4 + 5H2O→ CuSO4.5H2O
After that filtering the crystals with filter paper, it aims to separate the liquid phase of the formed
crystals and then wash the crystals with aquadest. By using equations of rendemen in which the
mass is practically divided by mass in theory multiplied by 100%, the result is 66,79% of the
crystallized crystals. Percent yield obtained less than 100%, because at the time of the experiment
The heating is less long so that Cu in the copper wire there is not all that soluble.
Conclusion:The conclusions of this experiment are:
1. The terine salt (CuSO4.5H2O) can be prepared by crystallization technique using concentrated
H2SO4 and concentrated HNO3, where the copper sulphate salt (CuSO4) is dark blue.
2. The yield obtained is 66.79%
