I think it’s Carbon dioxide
A. N₂ (g) + 3 H₂ (g) --> 2 NH₃ (g)
B. The value for standard enthalpy of formation is empirical given that the reactants involved were pure elements. So, you can search this on the internet or in any textbook. The Hf for NH₃ is -46.0 kJ/mol.
C. C (s) + O₂ (g) --> CO₂ (g)
D. The Hf for CO₂ is <span>-393.5 kJ/mol
E. 4 Fe (s) + 3 O</span>₂ (g) --> 2 Fe₂O₃ (s)
F. The Hf for solid Fe₂O₃ is -826.0 kJ/mol.
G. C (s) + 2 H₂ (g) --> CH₄ (g)
H. The Hf for methane gas is -74.9 kJ/mol.
Answer:
in the presence of a base
Explanation:
<em>Phenolphthalein will turn pink </em><em>in the presence of a base.</em>
<u>Phenolphthalein is an indicator that is used in acid/base titration to indicate end points. It responds to pH changes by changing its color. In basic solutions, the compound turns pink while it remains colorless in acidic medium. It has the chemical formula </u>
<u>.</u>
Phenolphthalein is considered a weak acid ordinarily and it ionizes incompletely in aqueous solution.

Addition of hydrogen ions shifts equilibrium to the left and the solution remains colorless while the addition of hydroxide ion removes the hydrogen ion and shifts the equilibrium to the right, giving pink coloration.
Divide measured yield by calculated yield
140/176 = 79.55%