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Consider the reaction below: 2 K(s) + Cl2(g) → 2 KCl(g)  ΔHrxn = –873.0 kJ  How much heat is released if 5.00 moles of potassium metal reacts with excess chlorine gas?

Consider the reaction below: 2 N2(g) + O2(g) → 2 N2O(g)     ΔHrxn = +163.2 kJ How much heat is absorbed if 5.00 moles of nitrogen gas reacts with excess oxygen gas?

A sample of sodium hydroxide, NaOH(s), dissolves in water, releasing heat to the surrounding water, and causing the temperature of the water to rise by 20 °C.  If the heat change for the reaction is –300 J, what is the heat change for the surrounding water?

Consider the reaction below: 4 Fe(s) + 3 O2(g) → 2 Fe2O3(s)       If 44.2 grams of oxygen react with an excess of iron metal, what mass of Fe2O3 can form?  (Hint: Fe2O3= 159.70 g/mol)

The tick Ixodes scapularis is the primary transmitter of Lyme disease in the northeastern United States. These ticks cause numerous infections each year because they feed on multiple hosts throughout their life cycle (and can become infected from the host). In addition, the ticks can acquire the bacteria via vertical transmission.

Consider the following equilibrium reaction: N2(g) + O2(g) ⇌ 2 NO(g)     ΔHrxn = +32.3 kJ In which direction will the following changes cause the equilibrium to shift, respectively? add N2 add NO raise the temperature [Note: Right is (R) or Left is (L)]

Choose the corresponding formal command for each sentence.   Dormir bien en el Hotel Intercontinental.

Choose the correct Direct Object Pronoun to answer the question.    ¿La dueña conoce a todos los empleados, incluidos nosotros? Sí, ella ______ conoce.

Choose PRETERITE or IMPERFECT to complete the paragraph.    Estela (1) [1] leyendo un libro cuando Tomás la (2) [2] por teléfono. Tomás la (3)[3] a ir a un restaurante esa noche. Estela (4)[4] mucha tarea que hacer, pero (5) [5]la invitación de Tomás.             Tomás (6) [6] a las ocho y ellos (7)[7].   (8)[8] buen tiempo y ellos (9)[9] caminar al restaurante. Mientras (10)[10] por la calle, se (11)[11]cariñosamente. Entonces, Tomás (12)[12] un regalo pequeño de su chaqueta y se lo (13)[13] a Estela. Estela (14)[14] el regalo rápidamente. (15)[15] un reloj. La semana pasada Estela (16) [16]su reloj y por eso (17)[17]un reloj nuevo.             Estela le (18)[18]:“¡Muchas gracias”! a Tomás y ellos se (19)[19]y se (20)[20] allí en la calle. Entonces, (21)[21] al restaurante y (22)[22] una cena excelente.

Complete the paragraph with the appropriate preterite form of each verb to find out what happened. (HINT!  All of theses are irregular verbs in the preterite tense.)   Roberto [1] (decir) que se levantó temprano el sábado pasado y [2] (ir) al centro con su amigo Gonzalo. Los dos hombres [3] (traer) sus tarjetas de crédito. Cuando Roberto entró a su tienda favorita, [4] (saber) inmediatamente que muchas cosas estaban en rebaja. Él [5] (estar) en la tienda por tres horas. ¡Le encanta gastar dinero!