C₄H₉OH + HBr = C₄H₉Br + H2O
Δmole of alcohol gives 1 mole of bromobutanol
HBr is in excess, so the yield of the product is limited by the alcohol
Wt. of 1 butanol = 18
Molar mass of the butanol = 74.12 g/mole
Moles of the alcohol = 1/74.12 = 0.01349 moles
So, moles of bromobutane = 0.01349 moles
Molar mass of C₄H₉Br = 137.018 g/moles
So, theoretical mass of bromobutane is = 0.01349 × 137.0.18
= 1.85 g
B. The sand increases friction by increasing roughness.
Answer: when reactants and products are gases at STP.
Justification:
1) STP stands for standard temperature (0°) and pressure (1 atm).
2) According to the kinetic molecular theory of the gases, and as per Avogadro's principle, equal volumes of gases, at the same temperature and pressure, have the same number of molecules.
3) Since the coefficients in a balanced chemical equation represent number of moles, when reactants and products are gases at the same temperature and pressure, the mole ratios are the same that the volume ratios, and then the coefficients of the chemical equation represent the volume ratios.
