# Chemistry

If a current of 2.5A flows for 2hrs
45mins through a water voltameter.
Determine the volume of
hydrogen gas at s.t.p. [molar volume
of gasesat s.t.p = 22.4dm3.?

1. 👍 0
2. 👎 0
3. 👁 112
1. 2.75Hr*(60min/Hr)*(60s/min)=9,900s

C=charge=current*time(s)=2.5A*9,900s=24750 C

24750*(mole/9500)=0.25648moles

1 mole=22.4L at STP

0.25648*22.4=5.74L

1. 👍 0
2. 👎 0
2. 5.74dm3=5.74L

1. 👍 0
2. 👎 1
3. seconds = 2 (3600) + 45 * 60 = 9900 seconds
coulombs = current * time = 2.5 * 9900 = 24750 Coulombs
How many electrons?
24750 Coulombs ( 1 electron / 1.6*10^-19 coulombs)
= (2.475 /1.6) 10^23 electrons
Each H+ needs one electron so each H2 molecule needs two
do we get 7.73 * 10^22 H2 molecules
How many mols is that?
6 * 10^23 molecules/mol
so
7.73*10^22 molecules ( 1 mol / 6*10^23 molecules) = 0.129 mol
0.129 mol * 22.4 liter/mol = 2.9 liters

1. 👍 1
2. 👎 0
4. Check arithmetic. I did that fast.

1. 👍 0
2. 👎 0
5. an A (ampere) is a Coulomb of charge per second
... there are 9.5E4 Coulombs in a mole of electrons

each mole of H2 requires two moles of electrons

moles elec = 2.5 * 2.75 * 60 * 60 / 9.5E4

calculate moles elec , divide by two for moles of H2

1. 👍 1
2. 👎 0
6. but Anon you need 2 mols of electrons for one mol of H2

1. 👍 0
2. 👎 0
7. The correct answer is 2.87 L.
2.75 x 60 x 60 x 2.5 = 24,750
96,485 C will release 22.4/2 = 11.2 L H2 @ stp.
11.2 L x (24,750/96,485) = 2.87 L H2 @ stp.

1. 👍 2
2. 👎 0
8. So, sorry. I didn't pay ful l attention. It's H2 so 1 atom contains 2 electrons. So, 1 mole of a H2 gas at STP will contain 2 moles of electrons.

2.75Hr*(60min/Hr)*(60s/min)=9,900s

C=charge=current*time(s)=2.5A*9,900s=24750 C

24750*(mole/9500)=0.25648moles

*****Correction

1 mole= 2 moles of e^-=22.4L at STP

0.25648 moles of e^-*(22.4L/2 moles of e^-)=2.87=2.9L

All of the calculations that gave you 2.9L are correct.

1. 👍 1
2. 👎 0

## Similar Questions

1. ### math

type 8580 words in 2hrs and 45mins

asked by josh on October 3, 2011
2. ### physics

Consider the circuit in the diagram. Let R1 = 51.0 Ω, R2 = 38.0 Ω, R3 = 74.0 Ω, R4 = 16.0 Ω, and V = 84 V. (b) What current flows from the battery? (c) What is the potential difference between points A and B? (d) What current

asked by opp on September 25, 2012
3. ### motion problem

A man rowed 30km downstream. it took him 2hrs more time in going back than in going downstream. if the current is 2kph, what is his speed in still water? (with solution pls... tnx)

asked by MNHS MNHS on November 12, 2013
4. ### AP Chemistry

Water is being electrolysed in the presence of a non-reactive electrolyte under standard conditions. If 2.5 amperes of current flows through the circuit for 13.6 minutes at 25 degrees celsius and 1 atmosphere, what volume of

asked by Toni on January 26, 2013
5. ### maths

A large pipe has a diameter of 9.8×10^2cm.Water flows in the pipe at a speed of 5m s^-1.Find the volume in m^3,of water that flows out from the pipe every second,correct to 2 significant fogures.[Take pai as 3.142]

asked by ashley on January 11, 2014
1. ### Physics

Water flows through a pipe of radius 4 cm at a rate of 3.5 m/s. Suppose each water molecule is singly ionized (highly unrealistic). a) What is the electric current density associated with the flow of these ions? b) What is the

asked by Jake on July 10, 2017
2. ### Physics

Water flows through a pipe of radius 4 cm at a rate of 3.5 m/s. Suppose each water molecule is singly ionized (highly unrealistic). What is the electric current density associated with the flow of these ions? What is the electric

asked by Lindsey on March 18, 2013
3. ### Physics

At one instant, a current of 8.0 A flows through part of a circuit as shown in the figure below. Determine the instantaneous potential difference between points A and B if the current starts to decrease at a constant rate of 1.0

asked by AAA on April 17, 2020
4. ### physics

The maximum permissible current through a galvanometer (G) of resistance 10ohmams is 0.05A. A resistance (R) is used to convert G into a voltameter with a maximum reading of 100v . find the value of R and how it is connected to G

asked by POPPY on April 3, 2019
5. ### Physics

At one instant, a current of 8.0 A flows through part of a circuit as shown in the figure below. Determine the instantaneous potential difference between points A and B if the current starts to decrease at a constant rate of 1.0

asked by AAA on April 17, 2020

More Similar Questions