A alkaloid compound contains 74.02% C, 8.710% H and 17.27% N. The empirical formula of the compound is___.
If 40.57 grams of it contains 0.2500 moles, then it's molecular formula will be:______.

Chemistry 11 Solutions

978Ͳ0Ͳ07Ͳ105107Ͳ1Chapter 8 Solutions and Their Properties • MHR | 85

Amount in moles, n, of the NaCl(s):

NaCl

2.5 g

m

n

M

58.44 g

2

4.2778 10 m l

ol

o

/m

u

Molar concentration, c, of the NaCl(aq):

–2 4.2778 × 10 mol

0.100

0.42778 mol/L

0.43 mol

L

/L

n

c

V

The molar concentration of the saline solution is 0.43 mol/L.

Check Your Solution

The units are correct and the answer correctly shows two significant digits. The

dilution of the original concentrated solution is correct and the change to mol/L

seems reasonable.

Section 8.4 Preparing Solutions in the Laboratory

Solutions for Practice Problems

Student Edition page 386

51. Practice Problem (page 386)

Suppose that you are given a stock solution of 1.50 mol/L ammonium sulfate,

(NH4)2SO4(aq).

What volume of the stock solution do you need to use to prepare each of the

following solutions?

a. 50.0 mL of 1.00 mol/L (NH4)2SO4(aq)

b. 2 × 102 mL of 0.800 mol/L (NH4)2SO4(aq)

c. 250 mL of 0.300 mol/L NH4

+

(aq)

What Is Required?

You need to calculate the initial volume, V1, of (NH4)2SO4(aq) stock solution

needed to prepare each given dilute solution.

The dilution gives the relationship between the molarity and the volume of the solution. The volume of stock solution with a molarity of 1.50 mol/L is 50 mL.

Dilution is said to be the addition of more volume to the concentrated solution to make it less in molar concentration. This tells about the inverse and indirect relationship between the volume and the molar concentration of the solution.

Given,

Initial volume = V₁

Initial molar concentration (M₁) = 1.50 mol/L

Final volume (V₂) = 125 mL = 0.125 L

Final molar concentration (M₂)= 0.60 mol/L

The dilution is calculated as:

M₁V₁ = M₂V₂

V₁ = M₂V₂ ÷ M₁

Substituting the values in the above formula as

V₁ = M₂V₂ ÷ M₁

V₁ = (0.60 mol/L × 0.125 L) ÷ 1.50 mol/ L

V₁ = 0.05 L

= 50 mL

Therefore, 50 mL of stock solution is needed to make a 0.60 mol/L solution.

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Answer:

Blue or Purple color filter

Explanation:

Given that Sodium has an emission spectrum with wavelength ≈ 590nm and for a wavelength of 590nm  the color is yellow.

Hence To filter out the color ( yellow ) to enable the measurement of the Balmer series of hydrogen spectrum, we have to use a filter that possess the complementary color of yellow ( i.e. purple(RYB color model) or blue (RGB additive color model )

therefore color filter to be used = Blue or Purple

Answer:

nucleus is a collection of particles called protons,which are positively charged..and neutrons which are electrically neutral..electrons which are negatively charged..and neutrons are in turn made up of particles called quarks ..

Explanation:

hope this helps u ...

Answer:

The Nucleus is made up of protons and neutrons.

Answer:

0.012 moles of electrons were transferred

Explanation:

We can find the number of electrons transferred from the time in seconds and the current in Amperes using the equation:

n = I*t / F

Where n are moles of electrons transferred

I is current in Amperes = 0.2053A

t is time in seconds:

94.3min*(60s/1min) = 5658s

F is faraday constant 96485A*s/mol

Replacing:

n = 0.2053A*5658s / 96485A*s/mol

n = 0.012 moles of electrons were transferred

Moles are the mass per unit molar mass of compound. The number of moles of electrons that are transferred is 0.012 moles.

An electrolytic cell is a type of electrochemical cell that uses electrical energy from external sources to conduct the chemical energy in a cell.  

The moles transferred in electrolytic cells are measured as:

[tex]\rm n = \rm \dfrac{I\times t}{F}[/tex]

Given,

Current (I) in amperes = 0.2053 A

Time (t) in seconds = 5658 sec

Faraday constant (F) = 96485 A -s/mol

Substituting values in the equation above moles (n) can be calculated as:

[tex]\begin{aligned} \rm n &= \dfrac{ 0.2053 \times 5658 }{96485}\\\\&= 0.012 \;\rm mol\end{aligned}[/tex]

Therefore, 0.012 moles are transferred in this process.

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Answer:

a. 9.2

b. 4.4

c. 6.3

Explanation:

In order to calculate the pH of each solution, we will use the definition of pH.

pH = -log [H⁺]

(a) [H⁺] = 5.4 × 10⁻¹⁰ M

pH = -log [H⁺] = -log 5.4 × 10⁻¹⁰ = 9.2

Since pH > 7, the solution is basic.

(b) [H⁺] = 4.3 × 10⁻⁵ M

pH = -log [H⁺] = -log 4.3 × 10⁻⁵ = 4.4

Since pH < 7, the solution is acid.

(c) [H⁺] = 5.4 × 10⁻⁷ M

pH = -log [H⁺] = -log 5.4 × 10⁻⁷ = 6.3

Since pH < 7, the solution is acid.

Explanation:

here's the answer. I just plug the expression into my calculator and find the intercept to avoid the quadratic formula

Answer:

7.38*10^21

Explanation:

2Na+2H20=2NaOH+H2

nNa=0.0123

number of water moles: 0.012*6*10^23=7.38*10^21

Answer:

Explanation:

Na2CO3+Ca(NO3)2=CaCO3+2NaNO3

nNa2CO3=0.02

nCa(NO3)2=0.02

mCaCO3=0.02*100=2 gram

nNaNo3=0.04

Cm=2/15

From the calculation, the mass of the product is 2 g.

A chemical reaction occurs when two more substances are mixed together. In this case, the reaction is shown by; Ca(NO3)2 + Na2CO3 ----> CaCO3(s) + 2NaNO3.

Number of moles of Na2CO3 = 100/1000 L *  0.2 mol/L = 0.02 moles

Number of moles of  Ca(NO3)2 = 200/1000 L *  0.1 mol/L = 0.02 moles

Since the reaction is equimolar, amount of the product = 0.02 moles * 100 g/mol = 2 g

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Answer:

Low value for copper recovery

Explanation:

The percentage recovery is obtained from;

Percent recovery = amount of substance you actually collected / amount of substance you were supposed to collect × 100

Note that the fact that some of the copper nitrate solution splashed out of the beaker means that some amount copper has been lost from the system. This loss of copper leads to a lower value of copper recovered from solution.

Answer:

22.1

Explanation:

Step 1: Calculate the number of formula units of lithium nitrate

A 5.08 L solution contains 2.68 × 10²¹ formula units per liter.

5.08 L × 2.68 × 10²¹ formula units/1 L = 1.36 × 10²² formula units

Step 2: Calculate the number of nitrate ions

Lithium nitrate dissociates completely in water according to the following equation.

LiNO₃(aq) ⇒ Li⁺(aq) + NO₃⁻(aq)

The molar ratio of LiNO₃ to NO₃⁻ is 1:1. The number of nitrate ions is 1/1 × 1.36 × 10²² = 1.36 × 10²².

Then,

log (1.36 × 10²²) = 22.1

The number of nitrate ions are present in the following aqueous solution is 13.6x10²¹, and log(base 10) value of this is 22.2.

Those salts which are completely dissociate into their ions in the solution form will known as strong electrolyte.

Lithium nitrate is a strong electrolyte and it shows complete dissociation as:

LiNO₃ → Li⁺ + NO₃⁻

Given that,

1 liter of solution containing = 2.68 x 10²¹ formula unit

5.08 L of solution containing = 5.08 x 2.68 x 10²¹ = 13.6x10²¹ formula unit

So, number of nitrate ion in given solution = 13.6x10²¹ formula unit

Log(13.6x10²¹) = 22.1

Hence, required values are 13.6x10²¹ and 22.1.

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Answer:

Cs> Ba> Pb>Si> P>O

Explanation:

Recall that atomic size decreases across a period and increases down the group.

As we move from Cs to Ba, the atomic size decreases across the period. Lead is larger than silicon since atomic size increases down the group.

Between phosphorus and oxygen, phosphorus is larger than oxygen as you move across the period.

Answer:

I'll see it

Explanation:

Answer:

I don't know ❤️

Answer:

cis

Explanation:

Cis isomers are formed when the substituents on the carbons of the double bond are on the same side of the double bond, forming a U. Trans isomers have substituents on opposite sides of the double bond, forming a sideways Z.

Answer:

B

Explanation:

Ammonia is considered a base as it's pH is 11

Answer from Gauthmath

The  compound NH3 (Ammonia) can be classified as a weak Base. Below you can learn more about Ammonia.

Ammonia is a chemical compound which is derived from the combination of Nitrogen and Hydrogen. It is denoted by the chemical formula NH3.

Ammonia is a base and when it reacts with acids to gives out salts. Physically, It is a colorless gas with a distinct characteristic of a pungent smell.

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Answer:

2Ag(s) + 2H²S(g) + O2(g) ➡️ Ag2S(s) + 2H2O(g)

Explanation:

Sorry for my typo. but you understand

Answer:

The rate constant of an SN1 reaction depends on the nucleophile

The rate constant of an SN2 reaction does not depend on the nucleophile

Explanation:

Let us recall that in an SN1 reaction, the rate determining step involves only the alkyl halide substrate and not the nucleophile. Hence;

Rate = k[RX]

Therefore;

k= Rate/[RX]

For an SN2 reaction, the rate determining step involves both the nucleophile and the alkyl halide substrate.

Hence;

Rate = k[Nu-] [RX]

k= Rate/[Nu-] [RX]

Note that;

[Nu-] = concentration of the nucleophile

[RX] =concentration of alkyl halide substrate

k= rate constant

We can see from the above derivations that;

1) The rate constant of an SN1 reaction does not depend on the nucleophile

2) The rate constant of an SN2 reaction depends on the nucleophile

Answer:

NaoH= sodium hydroxide

Answer:

a. True

Explanation:

An atom can be defined as the smallest unit comprising of matter that forms all chemical elements. Thus, atoms are basically the building blocks of matters and as such determines or defines the structure of a chemical element.

Generally, atoms are typically made up of three distinct particles and these are protons, neutrons and electrons.

A chemical reaction can be defined as a chemical process which typically involves the transformation or rearrangement of the atomic, ionic or molecular structure of an element through the breakdown and formation of chemical bonds to produce a new compound or substance.

Hydrogen is the simplest chemical element that exists. The symbol for the chemical element hydrogen is "H" and it is a colourless, tasteless, odorless, and highly flammable gas.

It is a chemical element found in group (1) of the periodic table and as such it has one (1) electron in its outermost shell. Thus, hydrogen has an atomic number of one (1) and a single valence electron because it has only one (1) proton and one (1) electron in its nucleus.

In Stoichiometry, two hydrogen atoms interact to form a hydrogen molecule, with each atom having a single electron in the 1S orbital. These hydrogen atoms react with each other due to the presence of a balanced attractive and repulsive force, which produces a strong covalent bond (H-H) in the hydrogen molecule.

Energy is released in the form of heat when the electrons in the orbitals of the two (2) hydrogen atoms form a covalent bond (H-H); thus, it's an exothermic chemical reaction.

In this equilibrium, the chemical system will shift to the right in order to produce more NH₃.

The equilibrium constant of a reaction is defined as:

"The ratio between equilibrium concentrations of products powered to their reaction quotient and  equilibrium concentration of reactants powered to thier reaction quotient".

The reaction quotient, Q, has the same algebraic expressions but use the actual concentrations of reactants.

To solve this question we need this additional information:

For this reaction, K = 6.0x10⁻² and the initial concentrations of the reactants are:

[N₂] = 4.0M; [NH₃] = 1.0x10⁻⁴M and [H₂] = 1.0x10⁻²M

Thus, for the reaction:

N₂ + 3H₂ ⇄ 2NH₃

The equilibrium constant, K, of this reaction, is defined as:

[tex]K = \frac{[NH_3]^2}{[H_2]^3[N_2]}[/tex]

Where [] are concentrations in equilibrium.

And Q, is:

[tex]Q = \frac{[NH_3]^2}{[H_2]^3[N_2]}[/tex]

Where actual concentrations are:

[NH₃] = 1.0x10⁻⁴M

[N₂] = 4.0M

[H₂] = 2.5x10⁻¹M

Replacing:

Q = 1.6x10⁻⁷

As Q < K,

The chemical system will shift to the right in order to produce more NH₃

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Answer:

O2 is limiting reactant

Explanation:

To find the limiting reactant we need to convert the mass of each reactant to the moles using the formula weight. And, as 1 mole of C6H12O6 reacts with 6 moles of O2, we can know wich reactant will be over first (Limiting reactant) as follows:

Moles C6H12O6:

650g * (1mol/180.16g) = 3.608 moles C6H12O6

Moles O2:

650g * (1mol/32g) = 20.31 moles O2

Now, for a complete reaction of 3.608 moles of C6H12O6 are required:

3.608 moles C6H12O6 * (6mol O2 / 1mol C6H12O6) = 21.65 moles O2

As there are just 20.31 moles of O2,

Answer:

81°C

111°C

cyclohexane

Explanation:

Distillation is a process of separating two liquids based on differences in Bolling point. For two substances having different boiling points, they are collected as they are converted into vapour, condensed and move down the condenser one after the other.

Since the boiling point of cyclohexane is less than that of toluene, cyclohexane is collected first before toluene.

Answer:

Electro positivity increases down the group

Explanation:

since hydrochloric acid is an acid and calcium hydroxide is a base, we know that this is an acid base reaction. The ions will then dissociatiate and bond with one another.

Answer:

Answer is B) 20.0 moles

Explanation:

From the equation,

1 mole of Fe2O3 = 2 moles of Al

therefore 10.0 moles of Fe2O3 = 10×2

= 20.0 moles.

Answer:

The empirical formula is C4H8O

Explanation:

Step 1: Data given

Valproic acid is composed of C, H, and O

Mass of the sample = 0.165 grams

Mass of water = 0.166 grams

Mass of CO2 = 0.403 grams

Molar mass of water ( H2O) = 18.02 g/mol

Molar mass of CO2 = 44.01 g/mol

Atomic mass of C = 12.01 g/mol

Atomic mass of O = 16.0 g/mol

Atomic mass H = 1.01 g/mol (H2 = 2.02 g/mol)

Step 2: The equation

CxHyOz + O2 → CO2 + H2O

Step 3: Calculate the number of carbon in the sample

The carbon comes from CO2

Mass C = (12.01 g/mol/44.01 g/mol) * 0.403 grams

Mass C = 0.110 grams

Step 4: Calculate mass of hydrogen in the sample

The hydrogen comes from H2O

Mass H = (2.02/18.02) * 0.166 grams

MAss H = 0.0186 grams

Step 5: Calculate mass of O

The mass of O in the sample = Mass of sample - mass of H - mass of C

The mass of O = 0.165 grams - 0.110 grams - 0.0186 grams

The mass of O = 0.0364 grams

Step 6: Calculate moles

Moles C = 0.110 grams / 12.01 g/mol = 0.00916 moles

Moles H = 0.0186 / 1.01 = 0.0184 moles

Moles O = 0.0364/16.0 = 0.00228 moles

Step 7: Calculate empirical formula

We divide by the smallest amount of moles

C: 0.00916/ 0.00228 = 4

H: 0.0184/0.00228 = 8

O: 0.00228/0.00228 = 1

The empirical formula is C4H8O

Answer:

+0.151, spontaneous

Explanation:

Given that;

Co^2+(aq) + 2e ---->Co(s) -0.28 V

Pb^2+(aq) + 2e ---->Pb(s). -0.13 V

Hence Co is the anode and Pb is the cathode

E°cell = E°cathode - E°anode

So;

E°cell = -0.13 V - (-0.28 V)

E°cell = 0.15 V

The cell reaction is spontaneous since E°cell is positive.

Answer:

Cm = n/V

n(H2SO4) = 245/98 = 2.5 mol

Cm(H2SO4) = 2.5/1 = 2.5 M

Explanation:

Answer:

NaCN- basic salt

KNO3 - neutral salt

NH4Cl - acid salt

NaHCO3 - acid salt

Na3PO4 - acid salt

Explanation:

Salt hydrolysis a process by which salts react with water giving an acid and a base.

When we dissolve NaCN in water, we have;

NaCN + - ⇄ Na^+ + CN^-

KNO3 ------> K^+ + NO3^-

NH4Cl ------> NH4^+ + Cl^-

NaHCO3 -----> Na^+ + HCO3^-

Na3PO4 ----> 3Na^+ + PO4^3-

Note that if a salt is formed from a weak acid and a strong base, the salt will be a basic salt e.g NaCN formed from weak HCN and strong NaOH.

If a salt is formed from a strong acid and weak base, the salt will be acidic, e.gNH4Cl formed from weak NH3 and strong HCl.

If a salt is formed from a strong acid and strong base, the salt will be neutral, e.g KNO3 formed from strong KOH and strong HNO3.