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# Rate Constant and Periodic Trends

I need some help answering these two questions:
1. For the following balanced reaction, determine the rate expression and the rate constant, k, for it using the data given below.

2A + B +C yields D + 2E + F

Experiment [A] mol/L [B] mol/L [C] mol/L Rate (M sec-1)

1 1.50 x 10-3 2.00 x 10-3 1.20 x 10-4 6.50 x 10-5
2 1.50 x 10-3 2.83 x 10-3 1.20 x 10-4 1.30 x 10-4
3 3.00 x 10-3 2.00 x 10-3 2.40 x 10-4 3.25 x 10-5
4 3.00 x 10-3 2.00 x 10-3 3.00 x 10-4 2.08 x 10-5

2. The compound boron nitride (BN) is comparable in hardness to diamond. Based on periodic trends, atomic interactions, bonding, etc., is this expected. Please explain the answer.

#### Solution Preview

Please refer to the attached file. Cheers.

The rate law can be written as:

Rate = k [A]a [B]b [C]c

For experiment 1:
6.50 × 10-5 M s-1 = k (1.5 × 10-3 M)a (2.0 × 10-3 M)b (1.2 × 10-4 M)c Equation (1)

For experiment 2:
1.30 × 10-4 M s-1 = k (1.5 × 10-3 M)a (2.83 × 10-3 M)b (1.2 × 10-4 M)c Equation (2)

For experiment 3:
3.25× 10-5 M s-1 = k (3.0 × 10-3 M)a (2.00 × 10-3 M)b (2.40 × 10-4 M)c Equation (3)

For experiment 4:
2.08 × 10-5 M s-1 = k (3.0 × 10-3 M)a (2.00 × 10-3 M)b (3.0 × 10-4 M)c Equation (4)

Now, take equation (2) and divide it by equation (1).

Now, ...

#### Solution Summary

This in-depth solution shows step-by-step calculations in determining the rate constant. In addition, the atomic properties of boron nitride is analyzed for periodic trends and variety of structural shapes.

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