Water is not a very good solvent. true or false

Zinc metal is added to a flask containing aqueous hydrochloric acid. The flask contains 0.400 mole of HCl. How much hydrogen gas

dusya [7]

Answer:

0.4 g of hydrogen gas would be produced.

1. 0.48 mole of HCl is needed to react completely with 15.5 g of zinc.

2. HCl is the limiting reactant.

3. 2.61 g of zinc is in excess

Explanation:

From the balanced equation of reaction:

$Zn(s)+ 2HCl(aq) --> H_2(g) + ZnCl_2(aq)$

1 mole of Zn requires 2 moles of HCl to produce 1 mole of hydrogen gas.

15.5 g of zinc = 15.5/65.3 = 0.24 moles of zinc.

0.24 moles Zn is supposed to require 0.24 x 2 moles HCl which is equivalent to 0.48 moles HCl.

But only 0.400 mole of HCl is present. Hence, HCl is the limiting reagent. For complete reaction with 15.5 g of Zinc, 0.48 mole HCl would be needed.

0.400 mole of HCl will require 0.2 mole of Zn for complete reaction. This thus means that 0.24 - 02 = 0.04 mole of Zn is in excess.

0.04 mole Zn = 0.04 x 65.3 = 2.61 g excess Zn.

Now, since HCl is the limiting reagent;

2 moles of HCl is required to produce 1 mole of H2 according to the equation.

0.400 mole HCl will therefore yield 0.400 x 1/2 = 0.2 mole H2

0.2 mole H2 = 2 x 0.2 = 0.4 g H2

Hence, 0.4 g of hydrogen gas would be produced.

6 0

2 years ago

How to find how many electrons are in an element

Murljashka [212]

Explanation:

1) Locate the atomic number in the upper left corner of the square. The atomic number will tell you the number of protons

2) In a neutral state, the element will contain the same number of protons as it will electrons.

--> Boron (B) has an atomic number of 5, so it has 5 protons.

--> Having 5 protons (+1 charge each) means to be balanced, it must have 5 electrons (-1 charge each)

However, what if it's not in a neutral state?

If it's not in a neutral state, it will look something like this:

Ca ^ 2+

Btw, the "^" means that it will be written like it's an exponent. That confuses people sometimes.

Anyways, the "2+" means it's an ion with a positive charge of 2. For us to have a positive charge, it means it's lost two electrons (cause electrons are negative, so taking them away means we are left with a more positive charge).

To get the number of remaining electrons, subtract the 2 from the atomic mass. In this case, that would be 20.

20 - 2 = 18 electrons

Another example:

N ^3-

Atomic Number: 7

7 + 3 = 10 electrons.

Why did I add here instead of subtracting? It's cause the 3- means we have added electrons, resulting in the ion having a negative charge. It's got more electrons than usual.

Hopefully this helps a bit.

5 0

2 years ago

Why do you del cold when you get out of the pool?

Vera_Pavlovna [14]

The water on your skin is evaporating, pulling heat with it. This is called evaporative cooling.

6 0

3 years ago

Mass is measured against a standard by using a balance. a. True b. False

jok3333 [9.3K]

Mass is measured against a standard by using a balance. The statement given above is a fact. Therefore the answer among the choices is letter "A" or "A. True". I hope this helps you on your assignment.

6 0

2 years ago

Read 2 more answers

A gas that effuses through a porous cylinder 1.87 times faster than chlorine gas. what is the molar mass and identity.

Rufina [12.5K]

From the Graham's law of effusion;
R1/R2 = √MM2/√MM1
Molar mass of chlorine gas is 71
Therefore;
1.87= √ 71 /√mm1
= 1.87² = 71/mm1
mm1 = 71/1.87²
= 71/3.4969
= 20.3
Thus, the molar mass of the other gas is 20.3 , and i think the gas is neon

6 0

3 years ago