Which reaction can be used to calculate the enthalpy of formation of a substance? 2 (g)→ (g)+.5 2 (g)
(g)+.5 2 (g)→2 (g)
(g)+2 (g)→3 (g)
2 (g)+.5 2 (g)→2 (l)

Which real-world scenarios below represent physical and chemical changes? -running a car -exploding fireworks -mixing water and powdered drink mix -combining oil and vinegar to make salad dressing -taking aspirin for a headache -diluting bleach with water-digesting dinner-spreading peanut butter on bread

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?

Connect the whole numbers on the periodic table to indicate what they represent?