Ex 1

‫بسم ال الرحمن الرحيم‬ Name :ayedzahran : Group : Day

Experiment "Introduction to chemical laboratory :Density determination" : Observation and results .1 :A. Density of chunks Mass of metallic chunks Volume before adding chunks Volume after adding chunks (Volume of chunks (Density of metal

5.64 g 50 ml 52 ml 2 ml (1 2.82 g\ml (2

: B. Density of KBr solution :i. Preparation of solution Assigned % KBr 14% Mass of KBr 18.2 g Mass of beaker 226.25 g Mass of beaker & KBr 244.45 g Mass of beaker + KBr+ water 358.23 g (Actual % KBr 13.79% (3 :ii. Density determination Weight of empty graduated cylinder 43.5 g Graduate + solution 94.53 g (Weight of solution 51.03 g (4 Volume of solution 48 ml (Density of solution 1.06 g\ml (5 Temperature of solution 26 C Not: For experiment number , For calculation number , For the solution . of answers

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:Calculation Volume of chunks = Volume after adding chunks - Volume before (1( adding chunks 52ml-50ml =2ml = Density of metal= Mass of metallic chunks/ Volume of chunks (2( 5.64g/2ml = 2.82g\ml= Actual % KBr= Mass of KBr *100%\Mass of solution (3( 18.2g\131.98g*100% = 13.79% = Weight of solution= (Weight Graduate + solution( - Weight of empty (4( graduated cylinder 94.53g-43.5g =51.03g = Density of solution= Weight of solution\ Volume of solution (5( 51.03g/48ml=1.06g\ml =

:Answer the following questions .2 A( What is the density of water (1g\ml( in the following units (g\cm3: 1g\cm3 (1cm3=1ml (kg\m3: 1*103Kg\m3 (1g=10-3Kg,1cm3=10-6 (g\L: 1*103g\L (1ml=10-3L B( Name the factors affecting the density of pure substance and .solutions temperature increase volume increase density decrease -1 for solution: concentration of solute increase mass of solution -2 increase density increase C( A 10-g sample of metal is added to 50 ml of water in a graduated cylinder. The final volume in the graduated cylinder is 52.8 ml. Calculate the density of the metal. M=10g , V1=50ml , V2=52.8ml D=M/Vs Vs =V2-V1=52.8-50=2.8ml D = 10/2.8=3.57g\ml D( A sample with the mass of 25 g of KBr is dissolved in 75 g of water. Calculate the present by weight of KBr in the solution. MKBr = 25g , Mwater = 75g % by mass = MKBr *100%\( MKBr+ Mwater ( =25*100%\(25+100( = 25%

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