Calculate the enthalpy for this reaction: 2C(s) + H2() → C2H2(g)
ΔH° = ??? kJ

Given the following thermochemical equations:
C2H2(g) + (5/2)O2(g) → 2CO2(g) + H2O(ℓ)
ΔH° = -1299.5 kJ

C(s) + O2(g) → CO2(g)
ΔH° = -393.5 kJ

H2(g) + (1/2)O2(g) → H2O(ℓ)
ΔH° = -285.8 kJ

Scientist wants to react a barium chloride salt with an acid. to speed up the reaction, the scientist crushes the barium chloride salt until it is a fine powder. this speeds up the reaction by a. increasing the ph of the salt. b. increasing the surface area of the salt. c. increasing the pressure of the salt. d. increasing the temperature of the salt. im thinking more a not 100% sure

What would most likely be the transmittance of a 0.70 m solution of solute a?

How many mmols of tris-hcl are there in 100 ml of a 100 mm tris-hcl buffer solution at ph 8.1? note that the 100 mm refers to the sum of tris and tris-hcl concentrations?