D- a new substance forming
Step 1
The reaction is written and balanced:
4 Rb + O2 =>2 Rb2O
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Step 2
Define % yield of product (Rb2O) = (Actual yield/Theoretical yield) x 100
The actual yield is provided by the exercise = 39.7 g
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Step 3
Determine the limiting reactant. The molar masses are needed to solve this:
For Rb) 85.4 g/mol
For O2) 32 g/mol
Procedure:
4 Rb + O2 =>2 Rb2O
4 x 85.4 g Rb ----- 32 g O2
82.4 g Rb ----- X = 7.72 g O2 are needed
For 82.4 g Rb, 7.72 g O2 is needed, but there is 11.6 g O2. Therefore, O2 is the excess agent. Rb is the limiting reactant.
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Step 4
Determine the theoretical yield from the limiting reactant:
The molar mass Rb2O) 187 g/mol
Procedure:
4 x 85.4 g Rb ------ 2 x 187 g Rb2O
82.4 g Rb ------ X = 90.2 g Rb2O = Theoretical yield
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Step 5
% yield = Actual y./Theoretical y. x 100 = (39.7 g/90.2 g) x 100 = 44 % approx.
Answer: % yield = 44 %
Answer:
There are formed 98.05 g of MnCl₂
Explanation:
The reaction is this one:
MnO₂ + 4 HCl → MnCl₂ + 2 H₂O + Cl₂
First of all, determinate moles. Divide mass /molar mass
150 g / 36.45 g/m = 4.11 moles of HCl
Ratio between HCl and MnCl₂ is 4:1
4 moles of HCl produce 1 mol of Chloride
4.11 moles of HCl 'll produce (4.11 . 1)/ 4 =1.03 moles of chloride
Molar mass . Moles = Mass
Molar Mass MnCl₂ = 95.2 g/m
95.2 g/m . 1.03 moles = 98.05 grams
Answer:
B. Soap solution
Explanation:
Hardness of water refers to the degree of calcium and magnesium in the water. In other words, hard water contains excessive mineral contents. The degree of hardness of a water body can be measured using the SOAP TEST KIT.
Due to the formation of insoluble minerals, soap forms an exvessive substance in the presence of hardwater because the particles or minerals contained in the water is reacting to form something insoluble. Hence, a SOAP test kit can be used to test the hardness of water.
