QUESTION: Consider the reaction: N2 + 3 H2  2 NH3 How much NH3 is produced if 0.200 mol H2 is consumed? A. 0.133 mol, B. 0.300 mol, C. 2.00 mol Consider the reaction: N2 + 3 H2  2 NH3 How much NH3 is produced if 0.200 mol H2 is consumed? A. 0.133 mol, B. 0.300 mol, C. 2.00 mol PAUSE CLICK CONTINUED ON NEXT SLIDE

We can summarize this fact using the equation shown here. QUESTION: Consider the reaction: N2 + 3 H2  2 NH3 How much NH3 is produced if 0.200 mol H2 is consumed? A. 0.133 mol, B. 0.300 mol, C. 2.00 mol n1 c1 = n2 c2 Amounts of reactants and products involved in a reaction are directly proportional. The mole-to-mole ratio is implied by the coefficients in the balanced equation. Changes in the amounts of reactants and products involved in a reaction are directly proportional, and the proportionality is implied by the coefficients in the balanced equation. We can summarize this fact using the equation shown here. If substances 1 and 2 are involved in a reaction Then the ratio of the change in moles of substance 1 HIGHLIGHT n1 to the change in moles of substance 2. is equal to the ratio of the coefficient of substance 1 in the balanced equation HIGHLIGHT c1 to the coefficient of substance 2 in the balanced equation. HIGHLIGHT c2 We can rearrange this equation to solve for moles of substance 1... CLICK CONTINUED ON NEXT SLIDE

QUESTION: Consider the reaction: N2 + 3 H2  2 NH3 How much NH3 is produced if 0.200 mol H2 is consumed? A. 0.133 mol, B. 0.300 mol, C. 2.00 mol n1 c1 = n2 c2 c1 And we get n1 equals n2 times c1 over c2 BOX equation Let’s see how we can apply this equation to the question we’re working on... If you know the moles of a reactant was consumed, or the moles of product produced. Assign that to n2. CALLOUT “Known” Then, to figure out the corresponding change in moles of another substance, HIGHLIGHT n1 Simply multiply n1 by a conversion factor based on the coefficients of substances 1 and 2. HIGHLIGHT c1/c2 CALLOUT “ratio of coefficients” pointing to c1/c2 CLICK CONTINUED ON NEXT SLIDE n1 n2 x = c2

QUESTION: Consider the reaction: N2 + 3 H2  2 NH3 How much NH3 is produced if 0.200 mol H2 is consumed? A. 0.133 mol, B. 0.300 mol, C. 2.00 mol n1 c1 = n2 c2 c1 CLICK We’re given than 0.200 moles of H2 are consumed. CLICK This is our n2. We multiply it by a conversion factor CLICK CLICK so that we can determine the amount of ammonia produced. Since we’re interested in ammonia, we put the coefficient of ammonia in the numerator CLICK The coefficient of ammonia in the balanced equation. HIGHLIGHT 2 in balanced equation and 2 in numerator ... and put the coefficient of H2 in the denominator CLICK The coefficient of H2 in the balanced equation is 3. HIGHLIGHT 3 in balanced equation and 3 in denominator The ratio of coefficients serves as a conversion factor. SHOW CANCELLATION OF UNITS And the answer we get here is 0.133 moles of ammonia. Note that we keep three significant digits in our answer since the least precise term in our calculation, 0.200, has only three significant digits. The numbers 2 and 3 in the conversion factor are exact. Therefore, the correct answer is A. We say that the change in the amount of ammonia is 0.133 moles. More specifically, we say that 0.133 moles of ammonia are produced. CLICK PAUSE END RECORDING n1 n2 x = c2 2 mol NH3 0.200 mol H2 = x 3 mol H2 = 0.133 mol NH3

Video ID: 4-8-1 © 2008, Project VALUE (Video Assessment Library for Undergraduate Education), Department of Physical Sciences Nicholls State University Author: Glenn V. Lo Narrator: Funded by Louisiana Board of Regents Contract No. LA-DL-SELECT-13-07/08