1. S

    how to study

    whenever we study physics numericals,units,definition of quantities in chemistry and formulas,reactions practice should be done to it strong. but my problem is when we study physics i encounter examples in middle of chapter like numericals can i solve numericals when i finish reading chapter.
  2. C

    Percentage by mass of Aresenic

    Arsenic can be oxidized to arsenic (V) acid, H3AsO4. This acid oxidises I- ions to I2, which can be estimated by titration against a standard thiosulphate solution: As + 5HNO3  H3AsO4 + 5NO2 + H2O H3AsO4 + 2HI  H3AsO3 + I2 + H2O If 0.1058 g of a sample containing arsenic required 28.7...
  3. T

    Calculations involving moles and percentage yield

    Hello all! I'm just starting out on chemistry and I don't even know where I would begin with these questions: What volume of a 2.40 mol/L magnesium bromide solution would contain 3.40 x 10^23 atoms of bromine? The reaction of 2.0g of Br2 with 4.0g of F2 produced BeF5 in 45% yield. How many...
  4. S

    Percentage dilution question

    My mother is taking an antihistamine preparation containing Ketotifen. I am trying to determine how many milligrams of Ketotifen are contained in each milliliter of the preparation. Here is a pic of the package, showing the concentrations, click to maximize: Using the Ketotifen Fumarate...
  5. S

    Theoretical Yield and Percentage Yield

    2.5 g of V2O5 was dissolved in 10mL of water, 5mL of H2SO4 and 15mL of ethanol. After being heated on a steam bath the solution was filtered and the filtrate was transferred to a 400mL beaker. 6.2 mL of acetylacetone was added and then the solution was neutralised by 10mL of Na2CO3. The product...
  6. H

    percentage yield

    A student heat 4g of Ca(NO3)2 for 15 min, after cooling mass of residue is 2.92g. How to calculate the percentage yield of CaO? the ans given is 41 %