Find unknown metal
A metal " M " is one of the most commonly used metals in the world. It accounts for 95% total of produced metals around the world. Because of its low cost and practical uses, it plays an important part in many industries and constructions. It also exists in the human body, mainly the bloodstream.
To identify M , people let 11.2 grams of M reacts with hydrochloric acid ( H C l ). The products are the chloride salt of M and 4.48 liters (at standard conditions) of hydrogen (gas).
Identify M using all the information above, and choose the best answer.
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1 solution
@Tin Le , you can use \ce{ } (I think it stands for "chemical equation") in LaTex for reaction equation. For example: \ce{CaCO3 (s) + H2SO4 (aq) -> CaSO4 (s) + CO2 (g) + H2O (g)} C a C O X 3 ( s ) + H X 2 S O X 4 ( a q ) C a S O X 4 ( s ) + C O X 2 ( g ) + H X 2 O ( g ) . Note that the element is not in italic and you don't need to enter the subscripts.
Also \ce{Fe + 2HCl -> FeCl2 + H2} F e + 2 H C l F e C l X 2 + H X 2 . Note that there is a space between 2 and HCl automatically inserted.
Assume the valence of M is n , and its chemical formula is also M .
Therefore, the chemical formula of the chloride salt of M is M C l n
The chemical reaction happened is: 2 M + 2 n H C l → 2 M C l n + n H 2
After the reaction, the amount of hydrogen gas we get is: n H 2 = 2 2 . 4 4 . 4 8 = 0 . 2 ( m o l )
From the chemical reaction, we can see that each 2 moles of M react creating n mole(s) of hydrogen gas.
Therefore, the amount of M participating in the reaction is: n M = n 0 . 2 × 2 = n 0 . 4
Hence the molar mass of M is M M = n 0 . 4 1 1 . 2 = 2 8 n
Round the molar mass of the given answers to the nearest whole number (as 28 and n are both whole numbers). Divide them to 28, and check if you get the whole value. If you indeed get the whole value, that is the answer.
(Or you can deduce which metal is it)
The answer is F e