At 25°C, the equilibrium constant Kc = 0.0012 for the reaction  B(aq) + C(aq)  ↔  2A(aq)     A solution of 0.80 M of B and 0.80 M of C is mixed and allowed to come to equilibrium. A student does the following steps below to calculate the equilibrium concentration of A.  There is one error in this calculation. Identify the step where the student made an error.  (keeping extra digits until the end of the calculation is not an error).

One of the four primary reasons for using compression reinforcement in beams is inadequate fire rating.

Which symbol represents the distance from the extreme compression fiber to the centroid of the longitudinal compression steel?

Paso 2 (4 pts) (1 pt per sentence: 0.5 pts meaning, 0.5 pts form)  Macarena is now telling José about her childhood. Complete each sentence with the most appropriate and correct imperfect form of one of the verbs given. Do not change the subject and use each verb only once. 

You are considering a beam design that has dimensions of b = 16 in., h = 24 in., and d = 21.5 in. The beam is singly reinforced with all of the reinforcement in a single row. The concrete strength is 6,700 psi, and the yield strength of the reinforcement is 60,000 psi. What cross-sectional area of reinforcement is needed to achieve a strain in the reinforcement of 0.0075?

Another word for excessive exaggeration is:

Which symbol represents the distance from the extreme fiber in compression to the centroid of the longitudinal reinforcement on the tension side of a reinforced concrete member?

A simply supported beam with dimensions of b = 12 in., h = 24 in., d = 21.5 in., and L = 21 ft supports a uniform service (unfactored) dead load consisting of its own weight plus 1.7 kips/ft and a uniform service (unfactored) live load of 1.5 kips/ft. The concrete is normal-weight concrete. Determine the moment due to the factored loads, Mu.      

A beam has dimensions of b = 16 in., h = 24 in., and d = 21.5 in. and is reinforced with 2 No. 6 bars. The concrete strength is 7,000 psi, and the yield strength of the reinforcement is 60,000 psi. If the depth of the compressive stress block is a = 0.554622 in. and the strain in the reinforcement is εs = 0.078407, determine the strength φMn for this beam. Assume the transverse reinforcement is not spirals.

Most concrete design codes specify a maximum usable compressive strain at which the nominal moment strength of the section is to be calculated. For ACI 318, this maximum usable strain value is 0.005.