(2007?Yueyang) The diagram shows part of the label of a laboratory reagent bottle of concentrated hydrochloric acid. Please answer the following questions: (1) the unopened reagent bottle of concentra

(2007?Yueyang) The diagram shows part of the label of a laboratory reagent bottle of concentrated hydrochloric acid. Please answer the following questions: (1) the unopened reagent bottle of concentrated hydrochloric acid (1) The mass of the concentrated hydrochloric acid in the bottle is: 500mL × 1.2g/mL = 600g;

(2) Let the mass of the hydrochloric acid solution diluted to 10% be x.

50mL × 1.2g/mL × 38% = x × 10%

x = 228g?

(3) Let the amount of hydrogen needed to produce 0.04g of hydrogen be y.

(2) The mass of hydrogen chloride is y.

(3) Let the amount of hydrogen needed to produce 0.04g of hydrogen be y. The mass of hydrogen chloride is y

Zn+2HCl═ZnCl2+H2↑

73 2

y 0.04g

< td style="border-bottom:1px solid black">73

y

=

2

0.04g

? y=1.46g

The solute mass fraction of this dilute hydrochloric acid=

1.46g

20g

× 100% = 7.3% <10%, so the mass fraction labeled on the reagent bottle is not accurate.

So the answers are:

(1) 600g; (2) 228.(3) Inaccurate