Chemistry, 23.01.2022 18:00 tjames30

Which of the following is not a point of evidence that a chemical change has taken place 1. The chemical that go into the reaction change color
2. There is a drastic change in the temperature went to chemicals or mixed together no
3. The products from the chemical reaction change in size/ shape
4. A pungent other is produced from the reaction of two chemicals

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8 m/s because for him to get the same amount of energy as ray is putting out, bobby, who weighs half as much as ray, needs to run twice as fast.

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Answerthis solution will not form a precipitateexplanationsolubility equilbrium: pbf₂(s) ⇄ pb²⁺(aq) + 2 f⁻(aq)the solubility product expression is $k_{sp} = [\text{pb}^{2+}][\text{f}^- ]^2 = 4 \times 10^{-8}$ (we exclude solids from the equilibrium expression).now suppose we have the trial ion product q, which we can define as $q = [\text{pb}^{2+}]_{\text{initial}} \cdot [\text{f}^- ]^2_{\text{initial}}$ then, we can interpret q as the product of the concentration of the ions that we have and ksp as the product of the ion concentrations that are needed to form a saturated solution.if q > ksp, then that implies that there will be a surplus of ions that exceed the amount that is required to form a saturated solution. a precipitate will then form (the precipitate continually forms until the surplus ions are removed and q is decreased to ksp's value).if q = ksp, the saturated solution that forms is barely saturated and the precipitate will be minimal.if q < ksp, then the ion concentration will not be enough to form a saturated solution (so no precipitate).using our information, we calculate the trial ion product: $\begin{aligned} q & = [\text{pb}^{2+}]_{\text{initial}} \cdot [\text{f}^- ]^2_{\text{initial}} \\ & = (1.9 \times 10^{-3} ) (3.8\times 10^{3})^2 \\ & = 2.7 \times 10^{-8} \end{aligned}$ since q = 2.7 × 10⁻⁸ < ksp = 4 × 10⁻⁸, a precipitate will not form.

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Unbalanced equation: fe2o3+ cofe + co21 fe2o3 + 3 co = 2 fe(s) + 3 co212.8g fe2o3 x (1 mol fe2o3 / 159.7g fe2o3) = 0.08015 mol fe2o311.5g co x (1 mol co / 28.01g co) = 0.4106 mol cofrom the balanced equation, 1 fe2o3 reacts with 3 cosince we have 0.08015 mol fe2o3 we therefore need0.08015 mol fe2o3 x (3 mol co / 1 mol fe2o3) = 0.2404 mol cosince we have 0.4106 mol co but only need 0.2404 to completely consume all thefe2o3, we have xs (excess) co and fe2o3 is therefore the limiting reagentfrom the balanced equation, 1 fe2o3 = 2 fe(s)0.08015 mol fe x (2 mol fe(s) / 1 mol fe2o3) = 0.1603 mol fe(s)theoretical mass of fe .1603 mol fe x (55.84g fe / mole fe) = 8.951g fe% yield = (6.10g / 8.951g) x 100% = 68.1%i didn't do this work, so i am not one hundred percent sure if it is correct seems like a reliable website,

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