Binary compounds of alkali metals and hydrogen react with water to liberate H₂(g). The H₂ from the reaction of a sample of NaH with an excess of water fills a volume of 0.490 L above the water. The temperature of the gas is 35 °C and the total pressure is 758 mmHg. Determine the mass of H₂ liberated and the mass of NaH that reacted.

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Hi everyone. So we have H. T. Gas From the actual potassium hydride with excess water and it fills a volume of 0.97 L above the water And at 40°C. A total pressure of gas is 780 of mercury glass. Kind of like the most of age to produce. And the mass of potassium hydride that reacted. So for this reaction and potassium hydride That's H. two L. And it's gonna be a potassium hydroxide plus H. Two. I need to complete the vapor pressure of hatching gas using the total pressure and vapor pressure of water which we can look up little bit of pressure of water. It's 55.3. Film means of mercury At 40°C. And the total paper pressure to get to the baby pressure of hydrogen gas. That's a bit pressure of water. 780 millimeters of mercury. If you consider very pressure of H. two, That's 55.3 millimeters of mercury. We subtract 55.3 kilometers american from both sides. What if I pressure H. 2? I'm gonna get 724 .7 mm on record and I need to complete the malls of hash and gas using the ideal gas law which is P. P. N. R. T. We can rearrange. This is all for N. And it goes PB. What about R. T. And is what we're looking for here. Our our constant 0.08, bizarre sex. There are some atmosphere about moles kelvin. The pressure 724.7 mm of Mercury. The volume is 0.97 leaders. And our temperature is 43 C. What we need to do first is convert our pressure into atmosphere of 724.7. That means of migrate Well 760 kilometers of marguerite in one atmosphere We get 0.9536 atmosphere. Now we need to cover our temperature into kelvin Have 40°C Plus 273.15. And get 313.15 K. People listen to the equation. I'm gonna get in. Was there a .95 36 atmosphere From 0.97 leaders By by 0.0806. There's some atmosphere by by Mose Kelvin. I'm standing 13. For n 0.036 Balls of H. two. Now we need to convert from moles of H. two. The malls protesting her job. Graham's protesting hydride 0.036 balls of age too. And in one mall of age too. One month potassium hard drive. And in one month potassium hydride you have the molar mass. This is 39.098 grams. That's 1.008 g. And we get 106g. We get 1.44 g potassium hydride. Thanks for watching my video and I hope it was helpful

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Key Concepts

Gas Laws

Stoichiometry

Molar Mass