Answer: 2.8
Explanation: just took the quiz
Moles of NaN3 at STP = volume of gas / 22.4 = 11.5/22.4 = 0.5mole. Massof NaN3 = moles of NaN3 x molecular weight = 0.5 x 65 = 32.5 grams.
M₁ = mass of water = 75 g
T₁ = initial temperature of water = 23.1 °C
c₁ = specific heat of water = 4.186 J/g°C
m₂ = mass of limestone = 62.6 g
T₂ = initial temperature of limestone = ?
c₂ = specific heat of limestone = 0.921 J/g°C
T = equilibrium temperature = 51.9 °C
using conservation of heat
Heat lost by limestone = heat gained by water
m₂c₂(T₂ - T) = m₁c₁(T - T₁)
inserting the values
(62.6) (0.921) (T₂ - 51.9) = (75) (4.186) (51.9 - 23.1)
T₂ = 208.73 °C
in three significant figures
T₂ = 209 °C
C. Formation of a new substance
Answer:
moles Fe₂O₃ = 0.938 mole
Explanation:
Convert given data to moles, solve in terms of moles by reaction ratios in balanced equation. After obtaining answer in moles, convert to needed dimension. In this case, no conversions are needed.
4Fe + 3O₂ => 2Fe₂O₃
105g/56g·mol⁻¹
= 1.875 mol Fe => => => => => => 2/4(1.875 mol Fe₂O₃) = 0.938 mol Fe₂O₃
