Which of the following measurements is written with two significant figures?

125 grams of HCl are used. Zn(s) + 2HCl(aq) = ZnCl2(aq) + H2(g). What is the percent yield if 1.2 moles of hydrogen are actually

Blababa [14]

Answer:

70%

Explanation:

To find the percent yield, you need to (1) convert grams HCl to moles (via molar mass from periodic table), then (2) convert moles HCl to moles H₂ (via mole-to-mole ratio from equation), then (3) calculate the percent yield H₂ (via percent yield equation).

Zn (s) + 2 HCl (aq) --> ZnCl₂ (aq) + 1 H₂ (g)

Molar Mass (HCl): 1.008 g/mole + 35.45 g/mole
Molar Mass (HCl) = 36.458 g/mole

125 g HCl 1 mole HCl 1 mole H₂
--------------- x ------------------ x ------------------ = 1.7 moles H₂
36.458 g 2 moles HCl

(actual yield / theoretical yield) x 100% = percent yield

theoretical/calculated yield = 1.7 moles H₂
actual yield = 1.2 moles H₂

(1.2 moles H₂ / 1.7 moles H₂) x 100% = 71%

Therefore, the best percent yield of hydrogen produced is 70%.

8 0

2 years ago

Which statement best defines kinetic energy? A. kinetic energy is highest at the highest point of structure or model.

Art [367]

Answer:

The answer is D. Kinetic energy is the energy of motion.

Pls mark brainliest. Hope this helped. :D

7 0

2 years ago

Read 2 more answers

Show how you might synthesize this compound from an alkyl bromide and a nucleophile in an SN2 reaction. Use the wedge/hash bond

PolarNik [594]

Answer:

See the image 1

Explanation:

If you look carefully at the progress of the SN2 reaction, you will realize something very important about the outcome. The nucleophile, being an electron-rich species, must attack the electrophilic carbon from the back side relative to the location of the leaving group. Approach from the front side simply doesn't work: the leaving group - which is also an electron-rich group - blocks the way. (see image 2)

The result of this backside attack is that the stereochemical configuration at the central carbon inverts as the reaction proceeds. In a sense, the molecule is turned inside out. At the transition state, the electrophilic carbon and the three 'R' substituents all lie on the same plane. (see image 3)

What this means is that SN2 reactions whether enzyme catalyzed or not, are inherently stereoselective: when the substitution takes place at a stereocenter, we can confidently predict the stereochemical configuration of the product.