Consider the reaction: A (g) + 1/2 B (g) → 2C (g) 

When C is increasing at a rate of 4.0×10⁻² M⋅s−1 how fast is B decreasing?      

  Express your answer using two significant figures.

 

How fast is A decreasing?

Express your answer using two significant figures.

B is decreasing at a rate of 1.0 x 10^-2 M/s ( or 0.010 M/s in decimal)

A is decreasing at a rate of 2.0 x 10^-2 M/s (or 0.020 M/s in decimal)

Step-by-step explanation

Given: r_c =4.0×10⁻² M/s

Required: -r_B, -r_A

Concept needed

-- given a reaction aA +bB --> cC

−arA??=−brB??=crC??

where - r_A -- rate of disappearance of reactant A

 - r_B -- rate of disappearance of reactant B

 r_C -- rate of appearance of product C

Chemical Reaction

A + 21?B --> 2C

Solution

-- applying the concept above

For reactant B

−21?rB??=2rC??

- r_B = 21?(2rC??)

       = 4rC??

       = 44.0×10−2?

       = 1.0 x 10^-2 M/s

For reactant A

−1rA??=2rC??

- r_A = 2rC??

       = 24.0×10−2?

       = 2.0 x 10^-2 M/s