Aflask containing helium gas is connected to an open-ended mercury manometer. the open end is exposed to the atmosphere, where the prevailing pressure is 752 torr. the mercury level in the open arm is 26 mm above that in the arm connected to the flask of helium. what is the helium pressure, in torr?

726 torr

Explanation:

Generally, atmospheric pressure can be measured using a manometer which is in form of a U-shaped tube. In addition, 1 mm Hg is equivalent to 1 torr. Therefore, 752 torr is equivalent to 752 mm Hg. Therefore, the total pressure will be equivalent to the atmospheric pressure (mm Hg) + the mercury height.

In this case, the mercury height = -26 mm

Thus:

The helium pressure = 752 - 26 = 726 mm Hg

This is also equivalent to 726 torr

2fe + 3h2so4 -> fe2(so4)3 + 3h2

it is necessary to balance equations in order to get the proper amount of reactants as well as products in order not to make a miscalculation.

you cannot change the subscripts as that would change the substance itself. for instance, diatomic elements such as h2 only have the subscript two when a gas. another example would be so4, if you were to change the subscript, the element would no longer be sulfate.

we change the coefficients instead as that only changes the number of molecules rather than the substance itself.

hope this !

fe 55.85 g/mol and h2o 18.02 g/mol.