General Chemistry Answers

Calculate the mass of water formed when 5.0 moles of oxygen reacts with excess hydrogen gas.

2H2+O2>2H2O

Using the unbalanced equation above calculate the moles of aluminum iodide produced from 2.4 moles of iodine vapor.

_Al(s) + _l2(g) > _Ali3(g)

Calculate the mass of water formed when 4.6 g of oxygen gas reacts with excess hydrogen gas.

2H2+O2>2H2O

How many moles of water are produced according to the reaction below given that you start with 18.3 g of CO2 and 61.0 g of KOH?

CO2+2KOH> K2CO3+H2O

A gas T=R a pleasure of 125 kpa and occupies soon! 10 hat is the new volume when the pleasure is changed to 95 kpa?

Assignment 2, Mark:  (10 %)

1. Consider the titration of Fe⁺² (0.02M, 50 ml) with standard Ce⁺⁴ (0.05M) monitored potentiometrically with Pt electrod, where reduction of Fe⁺² and Ce⁺³ occurs and SHE as a reference electrode. Calculate the potential change of the cell after 20 and 25 ml of Ce⁺⁴ additions.

2. In comparison of two methods for the determination of chromium in rye grass the following result were obtained: method 1: Mean = 1.48, Sd = 0.28, N=5; Method 2: Mean = 2.33; Sd = 0.31, N=5. The pooled standared diviation is given by Sp = 0.295.

A. Is there any significance difference between the two means?

3. 2.560 g of impure copper (II) sulphate sample was dissolved in water and precipitated with excess sodium hydroxide solution. If 1.245 g copper (II) hydroxide was obtained, what is the percentage of copper (II) sulphate in the impure sample? (Mwt; Cu = 63 g/mol, S = 32g/mol, O=16g/mol, Fe =56 g/mo

Assignment 1, Mark:  (10 %)

1. If 2g of NaCO3 dissolved in 1000ml of water, what is the normality of the solution?

2. How many equivalents of phosphoric acid are contained in 300 mL of 4.00 M phosphoric acid (Mwt = 98 g/mol)? (Assume the acid is to be completely neutralized by a base.)

3.                What is the pH after 20.0 mL of 0.010 M HCl is added to A buffer that contains both 0.250 M HF and 0.500 M NaF?

4.                Calculate the pH of the solution, when 50.0 ml of 0.5 M HNO₂ (Ka = 4.0x10^-4) mixed with 25.0 ml of 1.0 M KOH solution.

5. If 50 ml of 0.5M HCl solution titrated with 60 ml of 0.2 M of NaOH, what would be the pH of the final solution? 

Beryllium sulfate is a hydrated compound whose formula can be written BeSO4 • xH2O, where z is the number of moles of H2O per mole of BeSO4. When a 3.284 g sample of this hydrate was heated to 130°C for 10 minutes, all of the water of hydration was lost, leaving 1.948 g of anhydrous beryllium sulfate. Calculate the value of x, and write the formula and name of the hydrate.

A solution containing 3.75 mg/100 ml of X (335 g/mol) has a transmittance of 39.6% in a 1.50-cm cell at 425 nm. Calculate the molar absorptivity of X .