All categories

2 years ago

2. Calculate the mass of K in 90g of KOH

Chemistry

1 answer:

ValentinkaMS [17]2 years ago

8 0

KOH = 90g

KOH = 57 g/mol

K = 40g/mol

57g/mol contains 90 g

40g/mol will contain?

= 63.15 g

The mass of K is 63.15g

You might be interested in

A reaction is started with both reactants and products and proceeds in the reverse direction to reach equilibrium. Which of the

nekit [7.7K]

Answer:

Option A

Explanation:

A) Yes. The reaction reaches equilibrium when the rate of reaction of the reverse reaction is equal to the rate of the forward reaction , then the only cause for the reverse reaction to be favoured is that the initial rate of the reverse was greater than the forward one.

B) No. The rate constant of the reverse reaction can be greater than the forward one but the rate also depends on concentrations, thus a reverse reaction with greater rate constant can result in the net reaction proceeding in the forward reaction, the reverse reaction or be at equilibrium depending on the concentrations or reactants and products

C) No. A lower activation energy means a higher rate constant , but a higher rate constant does not mean that the net reaction will proceed to the reactants ( see point B)

D) No. The energy changes determine conditions under thermodynamic equilibrium and therefore the net direction of the reaction will depend on the temperature and concentrations of reactants and products with respect to the equilibrium conditions.

6 0

2 years ago

Consider the titration of 1L of 0.36 M NH3 (Kb=1.8x10−5) with 0.74 M HCl. What is the pH at the equivalence point of the titrati

worty [1.4K]

Answer:

Explanation:

The question asks to calculate the pH at equivalence point of the titration between ammonia and hydrochloric acid

Firstly, we write the equation of reaction between ammonia and hydrochloric acid.

NH3(aq)+HCl(aq)→NH4Cl(aq)

Ionically:

HCl + NH3 ---> NH4 + Cl-

Firstly, we calculate the number of moles of the ammonia as follows:

from c = n/v and thus, n = cv = 0.36 × 1 = 0.36 moles

At the equivalence point, there is equal number of moles of ammonia and HCl.

Hence, volume of HCl = number of moles/molarity of HCl = 0.36/0.74 = 0.486L

Hence, the total volume of solution will be 1 + 0.486 = 1.486L

Now, we calculate the concentration of the ammonium ions = 0.36/1.486 = 0.242M

An ICE TABLE IS USED TO FIND THE CONCENTRATION OF THE HYDROXONIUM ION(H3O+). ICE STANDS FOR INITIAL, CHANGE AND EQUILIBRIUM.

NH4+ H2O ⇄ NH3 H3O+

I 0.242 0 0

C -X +x +X

E 0.242-X X X

Since the question provides us with the base dissociation constant value K b, we can calculate the acid dissociation constant value Ka

To find this, we use the mathematical equation below

K a ⋅ K b = K w

, where K w- the self-ionization constant of water, equal to

10 ^-14 at room temperature

This means that you have

K a = K w.K b = 10 ^− 14 /1.8 * 10^-5 = 5.56 * 10^-10

Ka = [NH3][H3O+]/[NH4+]

= x * x/(0.242-x)

Since the value of Ka is small, we can say that 0.242-x ≈ 0.242

Hence, K a = x^2/0.242 = 5.56 * 10^-10

x^2 = 0.242 * 5.56 * 10^-10 = 1.35 * 10^-10

x = 0.00001161895

[H3O+] = 0.00001161895

pH = -log[H3O+]

pH = -log[0.00001161895 ] = 4.94

7 0

2 years ago

The diagram shows a simple lipid.

kifflom [539]

This is not a phospholipid as it does not contain a phosphate group at the end of the chain, and is not a triglyceride as there is no glyceryl moiety. Each carbon bonded to hydrogens makes the maximum number of C-H bonds possible, therefore there are no multiple bonds between carbons and the lipid is saturated. Therefore the answer is A.
Hope this helps!

7 0

3 years ago

Read 2 more answers

Capsaicin, the compound that gives the hot taste to chili peppers, has the formula C18H27NO3. Its molar mass is 305.42 g/mol. Ca

stellarik [79]

Molar mass = 305.42 g/mol

C = ( 12 x 18 / 305.42 ) x 100 => 70.72 % of C

H = ( 1 x 27 / 305.42 ) x 100 => 8.84 % of H

N = ( 14 x 1 / 305.42 ) x 100 => 4.58 % of N

O = ( 16 x 3 / 305.42) x 100 => 15.71% of O

hope this helps!

5 0

2 years ago

Read 2 more answers

Gaseous methane (CH4) will react with gaseous oxygen (O2) to produce gaseous carbon dioxide (CO) and gaseous water (H2O) . Suppo

Leto [7]

Answer:

0 g.

Explanation:

Hello,

In this case, since the reaction between methane and oxygen is:

$CH_4+2O_2\rightarrow CO_2+2H_2O$

If 0.963 g of methane react with 7.5 g of oxygen the first step is to identify the limiting reactant for which we compute the available moles of methane and the moles of methane consumed by the 7.5 g of oxygen:

$n_{CH_4}=0.963gCH_4*\frac{1molCH_4}{16gCH_4}=0.0602molCH_4\\ \\n_{CH_4}^{consumed}=7.5gO_2*\frac{1molO_2}{32gO_2}*\frac{1molCH_4}{2molO_2} =0.117molCH_4$

Thus, since oxygen theoretically consumes more methane than the available, we conclude the methane is the limiting reactant, for which it will be completely consumed, therefore, no remaining methane will be left over.

$left\ over=0g$

Regards.

7 0

2 years ago

2. Calculate the mass of K in 90g of KOH​

2. Calculate the mass of K in 90g of KOH