Answer to Question #208524 in General Chemistry for cece manGo

Question

1)    The theoretical maximum yield of MgCl₂ that could be formed from 5.00g Mg in the reaction,

Mg (s)+2HCl (aq)→MgCl₂ (aq)+H₂ (g)

is 19.6g. In a laboratory experiment, a student, was able to make 14.2g. What was the percentage yield?

2). A pressure of 101,325 Nm^-2 is equivalent to 1.00 atmospheres. Convert a pressure of 0.65 atmospheres to newton per metre squared (Nm^-2), giving your answer to 3 significant figures.

3). The relationship between concentration, amount of material (number of moles) and volume is,

Concentration (mol dm^-3)   =  moles (mol) / volume (dm³)

A solution contains 1.5 x 10^-2 mol of sodium hydroxide (NaOH) dissolved in 75.0 cm³ of water. What is the concentration of the sodium hydroxide solution?

 

4). The speed of light in a vacuum is 299,792,500 ms^-1. Convert to standard form and give the value to 3 significant figures.

 

Answer 1

% yield = Actual yield/Theoretical yield × 100

Theoretical = 19.6-5 = 14.6

Actual = 14.2

% Yield = 14.2/14.6 × 100

= 97.2%

2. 1 = 101,325

0.65 = ?

= 0.65 × 101325

= 65861.25Nm^-2

3). Concentration = Moles of solute /Littres of the solution

= 0.015

Molar Mass of NaOH = 39.997

= 0.015 × 39.997 = 0.6

= 0.0006+0.075

= 0.07506

= 0.015/0.07506

= 0.1998 mol/Littre

4. 299792500

= 3 × 10⁸ MS^-1