The zinc within a copper-plated penny will dissolve in hydrochloric acid if the copper coating is filed down in several spots (so that the hydrochloric acid can get to the zinc). the reaction between the acid and the zinc is as follows: 2h+(aq)+zn(s)→h2(g)+zn2+(aq). when the zinc in a certain penny dissolves, the total volume of gas collected over water at 25 ∘c was 0.953 l at a total pressure of 752 mmhg .

0.0746 grams of hydrogen

Explanation:

To calculate the mass of hydrogen :

(Vapor pressure of water is 23.78 mmHg at 25 ∘C )

According to avogadro's law, 1 mole of every substance occupies 22.4 L at NTP, weighs equal to the molecular mass and contains avogadro's number of particles.

According to the ideal gas equation:

P = Total Pressure = 752 mm Hg

pressure of hydrogen = Total Pressure - Vapor pressure of water =  (752 -23.78 )mm Hg = 728.22 mm Hg =  0.958 atm   (760mmHg=1atm)

V= Volume of the gas = 0.953 L

T= Temperature of the gas = 25°C = 298 K  

R= Gas constant = 0.0821 atmL/K mol

n= moles of gas= ?

Mass of

Thus 0.0746 grams of hydrogen is collected.

answer : a model is often used to explain and make things easier to understand when any scientific topic needs to be demonstrated and explained.

as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.

the answer is c. nacl