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3 years ago

This model shows a single unit of a compound containing several elements what is the chemical formula for the substance

Chemistry

1 answer:

Vinil7 [7]3 years ago

5 0

Explanation:

First Question

- The correct chemical formular is ; Al2(SO4)3

Second question

The following applies;

- The mass of the products is the same as the mass of the reactants

- At least one new product formed is a gas

- Molecules are changing into different molecules

Third Question

- Zn + HCl → ZnCl2 + H2

Fourth Question

- The atoms in the original substances regroup and form a different substance

- Matter is conserved

- The same atoms are present before and after the reaction

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What is the concentration in molarity of a solution that has 54.21g of calcium hydroxide dissolved in 560mL of water?

ra1l [238]

We know that Molarity = # mol/L

In the question, we are given grams - so we need to calculate the number of moles that we are dealing with. We can do this by first finding out what the molecular formula of calcium hydroxide is: $Ca(OH)_{2$

This means that we have 1 calcium and 2 hydroxides.

We can find the number of moles by taking the grams given divided by the molar mass of the molecule. We can find the molar mass of the molecule by taking each atomic mass of each atom (found on the periodic table) and adding them together:

Ca = 40.08g
O = 15.999g
H = 1.008g

We have 1 calcium, 2 oxygens, and 2 hydrogens. So let's add the atomic masses together:

40.08 + 2(15.999) + 2(1.008) = 74.094g

Now that we have the molar mass, we can find the number of moles due to already knowing the given amount in the question:

54.21g/74.09g = 0.73 moles of $Ca(OH)_{2}$

Now that we know the number of moles, we can solve for the molarity; The other part of the question gives us 560 mL of water - but this can quickly be converted to liters by moving the decimal to the left 3 places => 0.560 L

Knowing all of this information, we can plug it into the molarity equation:

Molarity = 0.73 mol/0.56 L
Molarity = 1.30

The molarity of the solution is 1.3 M.

4 0

3 years ago

Is soap more or less dense than water?

aksik [14]

The mass decreases but the volume stays the same

5 0

3 years ago

Consider the reaction below for which K = 78.2 atm-1. A(g) + B(g) ↔ C(g) Assume that 0.386 mol C(g) is placed in the cylinder re

borishaifa [10]

Answer:

1.65 L

Explanation:

The equation for the reaction is given as:

A + B ⇄ C

where;

numbers of moles = 0.386 mol C (g)

Volume = 7.29 L

Molar concentration of C = $\frac{0.386}{7.29}$

= 0.053 M

A + B ⇄ C

Initial 0 0 0.530

Change +x +x - x

Equilibrium x x (0.0530 - x)

$K = \frac{[C]}{[A][B]}$

where

K is given as ; 78.2 atm-1.

So, we have:

$78.2=\frac{[0.0530-x]}{[x][x]}$

$78.2= \frac{(0.0530-x)}{(x^2)}$

$78.2x^2= 0.0530-x$

$78.2x^2+x-0.0530=0$

Using quadratic formula;

$\frac{-b+/-\sqrt{b^2-4ac} }{2a}$

where; a = 78.2 ; b = 1 ; c= - 0.0530

= $\frac{-b+\sqrt{b^2-4ac} }{2a}$ or $\frac{-b-\sqrt{b^2-4ac} }{2a}$

= $\frac{-(1)+\sqrt{(1)^2-4(78.2)(-0.0530)} }{2(78.2)}$ or $\frac{-(1)-\sqrt{(1)^2-4(78.2)(-0.0530)} }{2(78.2)}$

= 0.0204 or -0.0332

Going by the positive value; we have:

x = 0.0204

[A] = 0.0204

[B] = 0.0204

[C] = 0.0530 - x

= 0.0530 - 0.0204

= 0.0326

Total number of moles at equilibrium = 0.0204 + 0.0204 + 0.0326

= 0.0734

Finally, we can calculate the volume of the cylinder at equilibrium using the ideal gas; PV =nRT

if we make V the subject of the formula; we have:

$V = \frac{nRT}{P}$

where;

P (pressure) = 1 atm

n (number of moles) = 0.0734 mole

R (rate constant) = 0.0821 L-atm/mol-K

T = 273.15 K (fixed constant temperature )

V (volume) = ???

$V=\frac{(0.0734*0.0821*273.15)}{(1.00)}$

V = 1.64604

V ≅ 1.65 L

3 0

3 years ago

When 12.71 g of copper react with 8.000 g of sulfur, 14.72 g of copper(I) sulphide is produced. What is the percentage yield in

Citrus2011 [14]

2Cu + S = Cu₂S

n(Cu)=m(Cu)/M(Cu)
n(Cu)=12.71/63.55=0.2 mol

n(S)=m(s)/M(S)
n(S)=8.000/32.01=0.25 mol

Cu:S 2:1
0.2 mol : 0.25 mol copper deficiency, sulphur in excess

theoretical mass of copper (I) sulfide
m(Cu₂S)=M(Cu₂S)n(Cu)/2

the percentage yield in the reaction is
w=m'(Cu₂S)/m(Cu₂S)=2m'(Cu₂S)/M(Cu₂S)n(Cu)
w=2*14.72/(159.16*0.2)=0.925 (92.5%)

5 0

3 years ago

which of the following has to remain constant to allow you to use the combine gas law for calculations?

kap26 [50]

Answer:

The amount of gas is what I came up with

5 0

4 years ago