What type of reaction is this? A. double replacemment B. Single replacement

A sample of pure oxalic acid (H2C2O4.2H2O) weighs 0.2000 g and requires 30.12 ml of KOH solution for

ValentinkaMS [17]

The molarity of KOH is 0.1055 M

calculation

Step 1: write the equation for reaction between H₂C₂O₄.2H₂O and KOH

H₂C₂O₄.2H₂O + 2 KOH → K₂C₂O₄ +4 H₂O

step 2: find the moles of H₂C₂O₄.2H₂O

moles = mass÷ molar mass

from periodic table the molar mass H₂C₂O₄.2H₂O= (1 x2) +(12 x2) +(16 x4) + 2(18)=126 g/mol

= 0.2000 g ÷ 126 g/mol =0.00159 moles

step 3: use the mole ratio to calculate the moles of KOH

H₂C₂O₄.2H₂O : KOH is 1:2

therefore the moles of KOH =0.00159 x 2 = 0.00318 moles

step 4: find molarity of KOH

molarity = moles/volume in liters

volume in liters = 30.12/1000=0.03012 L

molarity is therefore = 0.00318/0.03012 =0.1055 M

5 0

3 years ago

(I)how many atoms are present in 7g of lithium?

ICE Princess25 [194]

Answer :

(i) The number of atoms present in 7 g of lithium are, $6.07\times 10^{23}$

(ii) The number of atoms present in 7 g of lithium are, $1.204\times 10^{24}$

(iii) The number of moles of $F_2$ is, 1 mole

The number of moles of $CO_2$ is, 0.5 mole

The number of moles of $OH^-$ is, 1 mole

Explanation :

Part (i) :

First we have to calculate the moles of lithium.

$\text{Moles of }Li=\frac{\text{Mass of }Li}{\text{Molar mass of }Li}$

Molar mass of Li = 6.94 g/mole

$\text{Moles of }Li=\frac{7g}{6.94g/mol}=1.008mole$

Now we have to calculate the number of atoms present.

As, 1 mole of lithium contains $6.022\times 10^{23}$ number of atoms

So, 1.008 mole of lithium contains $1.008\times 6.022\times 10^{23}=6.07\times 10^{23}$ number of atoms

Thus, the number of atoms present in 7 g of lithium are, $6.07\times 10^{23}$

Part (ii) :

First we have to calculate the moles of carbon.

$\text{Moles of }C=\frac{\text{Mass of }C}{\text{Molar mass of }C}$

Molar mass of C = 12 g/mole

$\text{Moles of }C=\frac{24g}{12g/mol}=2mole$

Now we have to calculate the number of atoms present.

As, 1 mole of carbon contains $6.022\times 10^{23}$ number of atoms

So, 2 mole of carbon contains $2\times 6.022\times 10^{23}=1.204\times 10^{24}$ number of atoms

Thus, the number of atoms present in 7 g of lithium are, $1.204\times 10^{24}$

Part (iii) :

To calculate the moles of $F_2$ :

$\text{Moles of }F_2=\frac{\text{Mass of }F_2}{\text{Molar mass of }F_2}$

Molar mass of $F_2$ = 38 g/mole

$\text{Moles of }F_2=\frac{19g}{19g/mol}=1mole$

Thus, the number of moles of $F_2$ is, 1 mole

To calculate the moles of $CO_2$ :

$\text{Moles of }CO_2=\frac{\text{Mass of }CO_2}{\text{Molar mass of }CO_2}$

Molar mass of $CO_2$ = 44 g/mole

$\text{Moles of }CO_2=\frac{22g}{44g/mol}=0.5mole$

Thus, the number of moles of $CO_2$ is, 0.5 mole

To calculate the moles of $OH^-$ ions :

$\text{Moles of }OH^-=\frac{\text{Mass of }OH^-}{\text{Molar mass of }OH^-}$

Molar mass of $OH^-$ = 17 g/mole

$\text{Moles of }OH^-=\frac{17g}{17g/mol}=1mole$

Thus, the number of moles of $OH^-$ is, 1 mole

4 0

3 years ago

A 5-kg quantity of radioactive isotope decays to 2 kg after 10 years. Find the decay constant of the isotope.k = _____

Dvinal [7]

Answer:

k = -0.09165 years^(-1)

Explanation:

The exponential decay model of a radioactive isotope is generally given as;

A(t) = A_o(e^(kt))

Where;

A_o is quantity of isotope before decay, k is decay constant and A(t) is quantity after t years

We are given;

A_o = 5 kg

A(10) = 2kg

t = 10 years

Thus;

A(10) = 2 = 5(e^(10k))

Thus;

2 = 5(e^(10k))

2/5 = (e^(10k))

0.4 = (e^(10k))

In 0.4 = 10k

-0.9164 = 10k

k = -0.9164/10

k = -0.09165 years^(-1)

7 0

3 years ago

What law is known as the law of action- reaction?

Molodets [167]

Law of Action and Reaction mean "To every action there is equal and opposite reaction.

Explanation:

It is Newtons third law which explained few things such as :-

1. The nature of the forces between the two interacting objects.

2. According to this law , the force that is exerted from Object-1 to Object-2 is said to be equal in magnitude and opposite to the direction to the force exerted to object 2 upon object 1.

3. Eaxmple - As we push against the wall - Action , the wall in return opposes equal force to resist the pressure of the hand - Reaction.

6 0

3 years ago

If 25.0 mL of a 2.00 M CaCl2 solution is used for the reaction

RideAnS [48]

0.1 moles of chloride ions were involved in the reaction if 25.0 mL of a 2.00 M CaCl2 solution is used for the reaction.

Explanation:

Data given:

volume of Ca $Cl_{2}$ = 25 ml 0r 0.025

molarity of the calcium chloride solution = 2M

number of chloride ions =?

Balance chemical reaction:

Ca + 2 $Cl_{2}$ ⇒ $Ca_{} Cl_{2}$

number of moles in 25 ml is calculated as:

molarity = $\frac{number of moles}{volume}$

number of moles of calcium chloride = molarity x volume

putting the values in the equation:

number of moles = 2 x 0.025

= 0.05 moles of calcium chloride

1 mole of Ca $Cl_{2}$ decomposes as 1 calcium ion and 2 chloride ions

so 0.05 moles will have x moles of chloride ion

$\frac{2}{1}$ = $\frac{x}{0.05}$

x= 0.1

0.1 moles of chloride ions will be involved in the reaction.

5 0

3 years ago