What you need to do is like this:
ΔSrxn∘ = Products - Reactants
<span>ΔSrxn∘ = [NO2 (mols*S∘)] - [NO (mols*S∘) + O2 (mols*S∘)] </span>
<span>ΔSrxn∘ = [(2 mol * 240.0 J/mol*K)] - [(1 mol *205.2 J/mol*K) + (2 mol *210.8 J/mol*K)] </span>
<span>ΔSrxn∘ = [480 J/K] - [626.8 J/K] </span>
<span>ΔSrxn∘ = -146.8 J/K
</span>I hope this is good for you
She can prepare only C. milkshakes.
Toasting bread, scrambling eggs, and baking a cake all involve <em>chemical changes</em>.
Q1)
molarity is defined as the number of moles of solute in 1 L of solution.
the NaCl solution volume is 1.00 L
number of moles NaCl = NaCl mass present / molar mass of NaCl
NaCl moles = 112 g / 58.5 g/mol = 1.91 mol
the number of moles of NaCl in 1.00 L of solution is - 1.91 mol
therefore molarity of NaCl is 1.91 M
Q2)
molality is defined as the number of moles of solute in 1 kg of solvent.
density is mass per volume.
density of the solution is 1.08 g/mL.
therefore mass of the solution is = density x volume
mass = 1.08 g/mL x 1000 mL = 1080 g
since we have to find the moles in 1 kg of solvent
mass of solvent = 1080 g - 112 g = 968 g
number of moles of NaCl in 968 g of solvent - 1.91 mol
therefore number of NaCl moles in 1000 g - (1.91 mol / 968 g) x 1000 g/kg = 1.97 mol/kg
molality of NaCl solution is 1.97 mol/kg
Q3)
mass percentage is the percentage of mass of solute by total mass of the solution
mass percentage of solution = mass of solute / total mass of the solution
mass of solute = 112 g
total mass of solution = 1080 g
mass % of NaCl = 112 g / 1080 g x 100%
therefore mass % of NaCl = 10.4 %
answer is 10.4 %
7 grams of Oxygen. The Law of conservation of mass says that mass can be neither created nor destroyed, so the total mass of the products (in this case the oxygen plus the mercury) must equal the total mass of the reactants (in this case, the mercuric oxide).
