Chemistry Answers

A mass of 200 g of Zn reacts with 800.0 mL of 4.00 M HCl to form Zn(Cl)₂

Zn(s) + HCl (aq) → Zn(Cl)₂ (aq) + H₂ (g)

1.1      Balance the equation of the chemical reaction                                                                                   

1.2      Identify the liming reactant.                                                                                                                                  

1.3      Determine the excess reactant remaining after the reaction was complete.                                      

1.4      Calculate the theoretical yield.                                                                                                                             

1.5      Calculate the percentage yield for the production of H2. The actual yield obtained for H₂ was 1.46 g.

5.A balloon has a volume of 2.25 L when the temperature is 400C. What will be the volume if the balloon is cooled to 120C? Assume the pressure to be constant.

4. A 2.5 litre sample of a gas is heated from 250 C to 550C at constant pressure. Compute the volume at the higher temperature?

2. A tank ( not rigid) contains 2.5 litres of helium gas at 280C . At constant pressure, what will

be the volume of the tank after heating it and its content to 430C temperature?

1. What amounts of each species is expected to be present at the end of the reaction between 3.2 g of solid gallium and 3.2 g of gaseous oxygen? 
2. Elemental copper and HNO₃ react to form copper (II) nitrate, nitrogen dioxide, and water. What is the percent yield of the reaction where 0.185 Mg of copper and 0.0125 Tg of HNO₃ react to form 1.95 x 10²⁰ fg of nitrogen dioxide?
3. When 1.25g of H₂Se gas is bubbled into a solution containing 2.00g of potassium hydroxide, how many grams of the potassium-containing product forms, assuming that the reaction proceeds with 92.0% yield? 
4. Phosphorous and hydrogen react to form 4.00 g of product with 35.5 % yield. If 1.05 g of hydrogen remained unreacted, how much phosphorus must have been present at the start?
5. How many of each of the spectator ions are present after the reaction of 1.0g calcium sulfate and 1.0g potassium phosphate?

1.    What concentration of NaF do you need to add to a 0.15 M HF solution to get a buffer solution pH of 9.5? The Ka for HF is 7.4x10^-4.

6.4 oz of ZnO is 54% Zn. How many grams of ZnO does it contain?

Considering only ions with charges of +1, +2, -1, and -2, or neutral atoms, give the symbols for 4 species that are isoelectronic with Kr.

Calculate the volume of 0.25 of H2SO4 that will contain a 4.5g of the acid

10cm² of carbon (ii)oxide is sparked with 10cm² of oxygen. if all the volume of gases are measured at STP, calculate the volume of the residual gases after sparking