General Chemistry Answers

The mass of the calcium carbonate in 0.125 g stick of chalk is determined by dissolving the chalk in 50.0 mL of 0.20 M HCl and then titrating any excess HCl with a standardized solution of KOH. A volume equal to 32.12 mL of 0.250 M KOH is required to reach the endpoint. Write the complete computation.

A. How many millimoles of the excess HCl was back-titrated?

B. How many millimoles of HCl actually reacted to the CaCO3 in the chalk sample?

C. What is the percent by mass of calcium carbonate in the chalk?

Why is Sodium Bromide more soluble in water compared to Sodium Chloride?

The volume of 300 K sample of gas is raised from 3.0 L to 4.5 L. What will be the new temperature of the gas?

can you split N2O(g) and N2? i'm having this equation in thermochemistry (hess law) where i need to get N2(g) only but the product and reaction only has 3N2O(g) and 4N2(g).

1.     Calculate the freezing and boiling points of a solution prepared by dissolving   

     15.5 g of Al (NO₃)₃ in 200.0 g of water. (Molar mass of Al (NO₃)₃ is 212.996 g/mol). 

how many moles of no can be formed by reacting 5.0 moled of NO2?

How could the following pairs of isomeric compounds be differentiated by mass spectrometry?

2. Sample Calculations

From the data contained above in Table 2 above, and using the formula shown on Page 5, the following table below can be constructed. You must show in a sample calculation how you determined one set of values shown in Table A. 

2.1. Determine the amount (mg) of Carboxylesterase enzyme present in 50 μL (1 mark)

2.2. Determine p-npa substrate concentration (2 marks)

2.3. Velocity (v*) (2 marks)

2.4. 1/v* (1 mark)

2.5. 1/[p-npa] (1 mark)

  What is the oxidation number of the element in bold below:

   НCl; Н₂O ; Н₂

    Balance the following equation by the electron-balancing method. Name oxidizing and reducing agents:

NH₃ + O₂    = N₂ + H₂O