In the experiment "Preparation and Standardization of a Sodium Hydroxide Solution", why was the burette rinsed with NaOH before filling it to "zero" for the titration?

Answers

Answer 1

Answer: The correct option is ALL OF THE ABOVE.

Explanation:

TITRATION is a type of volumetric analysis which is used for determining the concentration of solutions. In this process a specific volume of a solution is placed in a conical flask by means of a pipette and small quantities of a second solution is slowly added from a burette until the end point is reached. This is determined by a means of an indicator which shows a characteristic colour change.

During titration, the following precautions should be followed to avoid errors and maintain standardisation in the experiment.

--> Any air bubble in the burette and pipette must be removed during measurement

--> the burette tap should be tightened to avoid leakage.

--> Remove the funnel from the burette before taking any reading to avoid errors in reading the volume.

--> use the base solution such as Sodium Hydroxide Solution to rinse the burette after washing with soap and tap water:

• to remove any air bubble and fill it's tip

• to remove any residual liquid from the water and soap solution which may interfere with the results of the experiment.

• to check if the burette is in good condition.

Therefore all of the above options to the question are correct.

In The Experiment "Preparation And Standardization Of A Sodium Hydroxide Solution", Why Was The Burette

Related Questions


Methanol has the formula CH3OH. What is the predominant intermolecular force between methanol molecules?
ANSWER:
dispersion forces
dipole forces
ionic bonds
hydrogen bonds

Answers

Answer:

hydrogen bonds

Explanation:

similarly CH3OH also has a OH group and H hydrogen thus it will also form h-bonding.

Which of the following is true for balancing equations?
A. There must be an equal number of atoms of each element on both sides of the equation.

B. The number of products should be equal to the number of reactants

C. The properties of products should be the same as the properties of the reactants

D. There must be an equal number of compounds on both sides of the equation

Answers

Answer:

A.

Explanation:

An equation with the equal amount and proportion of atoms of each element on both sides of the reaction is commonly referred to as a balanced chemical equation.

The law of conservation of matter asserts that no observable and empirical change in the amount of matter occurs within a conventional chemical process. As a result, each element in the product would have the same equal amount or numbers of atoms as the reactants.

Consider the following chemical equilibrium: Now write an equation below that shows how to calculate from for this reaction at an absolute temperature . You can assume is comfortably above room temperature. If you include any common physical constants in your equation be sure you use their standard symbols, found in the ALEKS Calculator.

Answers

Answer:

Kp=Kc *(RT)+-3

Explanation:

The relation between Kp and Kc is given below:

Where,

Kp is the pressure equilibrium constant

Kc is the molar equilibrium constant

R is gas constant , R = 0.082057 L atm.mol⁻¹K⁻¹

T is the temperature in Kelvins

Δn = (No. of moles of gaseous products)-(No. of moles of gaseous reactants)

For the first equilibrium reaction:

Δn = (0)-(2+1) = -3

Thus, Kp is:

Kp=Kc *(RT)+-3

What is the gravitational potential energy of a 1500-kg truck resting on top of a 550-m hill on earth?( earth’s gravitational pull is 9.8m/s2).

Answers

Answer:

E = 8085 kJ

Explanation:

Given that,

The mass of a truck, m = 1500 kg

Height, h = 550 m

We need to find the gravitational potential energy of the truck. It can be calculated as follows :

[tex]E=mgh[/tex]

Put all the values,

[tex]E=1500\times 9.8\times 550\\\\E=8085000\ J\\\\or\\\\E=8085\ kJ[/tex]

So, the gravitational potential energy is 8085 kJ.

define the following terms atom​

Answers

an atom is the smallest particle of all matter

Why do gases act more ideal at
lower pressures?

Answers

Answer:

Gases act more ideal at lower pressure beacuse the attractive forces between molecules will decrease or become less significant compared to the empty space between them.

Explanation:

Generally, a gas behaves more like an ideal gas at higher temperature and lower pressure as the potential energy due to intermolecular forces becomes less significant compared with the particles "kinetic energy" and the size of the molecules become less significant compared to the empty space between them.

Attractive forces between molecules, decrease the pressure of a reak gas, slowing the molecules and reducing collisions with the walls.The higher the value of a gas, the greater the attraction between molecules and the more easily the gas will compress.

HOPE IT HELPS MUCH

answered by: John Glenly Pillazo Mahusay

What is the product of the following reaction? K OC(CH3)3

Answers

Answer:

See explanation and image attached

Explanation:

The reaction is an E2 reaction. It is a synchronous reaction.

The base KOC(CH3)3 abstracts a proton as the bromide ion leaves in a single step.

This yields the product as shown in the image attached.

Give the number of lone pairs around the central atom and the molecular geometry of SCl2. Multiple Choice 3 lone pairs, linear 1 lone pair, bent 3 lone pairs, bent 0 lone pairs, linear 2 lone pairs, bent

Answers

Answer:

2 lone pairs, bent

Explanation:

According to the Valence Shell Electron Pair Repulsion Theory, the number of electron pairs on the valence shell of the central atom in a molecule influences the shape of the molecule.

The presence of lone pairs on the valence shell of the central atom causes the observed molecular geometry to deviate from the ideal geometry predicted on the basis of the valence shell electron pair repulsion theory.

SCl2 has four regions of electron density. This means that its electron domain geometry is tetrahedral. However, there are two lone pairs on the valence shell of the central atom hence the observed molecular geometry is bent.

The radius of a platinum atom is 139 pm. How many platinum atoms would have to be laid side by side to span a distance of 1.39 mm?

Answers

Answer:

5x10⁶ atoms of platium have to be laid side by side

Explanation:

1 atom of platium has a radius of 139pm = 139x10⁻¹²m. The distance that occupies 1 atom of platinum is 2 times its ratio:

139x10⁻¹²m*2 = 2.78x10⁻¹⁰m

Assuming there is no distance between to atoms of platinum, just its ratio. The amount of atoms necessary to occupy  1.39mm = 1.39x10⁻³m is:

1.39x10⁻³m / 2.78x10⁻¹⁰m =

5x10⁶ atoms of platium have to be laid side by side

important of organic chemistry in our daily life ​

Answers

Answer:

Human life has become very simple by using organic chemicals. The importance of organic chemicals in the daily life and industrial area can be explained as follows. (i) Food Vitamins, proteins, sugar, flour, fats etc. ... (ii) Agriculture is an important place for organic chemical for the growth of agricultural production.

Someone can you please please help me

Answers

Answer:

False

Explanation:

Target organ toxins are chemicals that can cause adverse effects or disease states manifested in specific organs of the body. Toxins do not affect all organs in the body to the same extent due to their different cell structures.

A sample of Br2(g) takes 12.0 min to effuse through a membrane. How long would it take the same number of moles of Ar(g) to effuse through the same membrane

Answers

Answer:

6 mins

Explanation:

The time taken for Ar to effuse can be obtained as follow:

Time for Br₂ (t₁) = 12 mins

Molar mass of Br₂ (M₁) = 2 × 80 = 160 g/mol

Molar mass of Ar (M₂) = 40 g/mol

Time for Ar (t₂) =?

t₂/t₁= √(M₂/M₁)

t₂ / 12 = √(40/160)

Cross multiply

t₂ = 12 × √(40/160)

t₂ = 12 × 0.5

t₂ = 6 mins

Therefore, it will take 6 mins for the same amount of Ar to effused out.

if salt and sand is mixed with distilled water, what will be the residue? and, what will be the filtrate?

Answers

Answer:

Filtration is a technique used as a remedy to separate mixes

Explanation:

If you have a sodium, then you will explore that salt dissolves but the sand is still the same.

If the salt in the resin water solution scanners, the sand remains the residue and passes through the filter paper.

All you have to do now is pleasant the salty water so that the water can evaporate, leaving the salt behind.

determine the mass in grams of 3.75 x 10^21 atoms of zinc. (the mass of one mole of zinc is 65.39 g)

Answers

Answer: The mass in [tex]3.75 \times 10^{21}[/tex] atoms of zinc is 0.405 g.

Explanation:

Given: Atoms of zinc = [tex]3.75 \times 10^{21}[/tex]

It is known that 1 mole of every substance contains [tex]6.022 \times 10^{23}[/tex] atoms. So, the number of moles in given number of atoms is as follows.

[tex]Moles = \frac{3.75 \times 10^{21}}{6.022 \times 10^{23}}\\= 0.622 \times 10^{-2}\\= 0.0062 mol[/tex]

As moles is the mass of a substance divided by its molar mass. So, mass of zinc (molar mass = 65.39 g/mol) is calculated as follows.

[tex]Moles = \frac{mass}{molar mass}\\0.0062 mol = \frac{mass}{65.39 g}\\mass = 0.405 g[/tex]

Thus, we can conclude that the mass in [tex]3.75 \times 10^{21}[/tex] atoms of zinc is 0.405 g.

A sample of brass, which has a specific heat capacity of , is put into a calorimeter (see sketch at right) that contains of water. The temperature of the water starts off at . When the temperature of the water stops changing it's . The pressure remains constant at . Calculate the initial temperature of the brass sample. Be sure your answer is rounded to significant digits.

Answers

Answer:

The initial temperature of the brass sample is 90.1°C

Note: The question is incomplete. A similar but complete question is given below :

A 52.9g sample of brass, which has a specific heat capacity of 0.375·J·g−1°C−1, is put into a calorimeter (see sketch at right) that contains 100.0g of water. The temperature of the water starts off at 15.0°C. When the temperature of the water stops changing it's 18.4°C. The pressure remains constant at 1 atm. Calculate the initial temperature of the brass sample. Be sure your answer is rounded to 2 significant digits.

Explanation:

Assuming that the calorimeter is an isolated system and that no heat is lost from the calorimeter. The total heat in the system is the sum of the heat content of the brass and that of water

Total heat lost by the brass = heat gained by the water

The quantity of heat lost or gained, Q = mcΔT

Where m = mass of the substance, c = specific heat capacity of substance, ΔT = temperature change

Heat gained by water is positive while heat lost by brass is negative

mass of brass = 52.9 g, specific heat capacity of brass = 0.375·J·g−1°C−1, ΔT = (18.4 - t °C; where t is the initial temperature), mass of water = 100.0 g, specific heat capacity of water = 4.186 J/g°C, ΔT = = 18.4 - 15.0 = 3.4 °C

Heat lost by brass z= - [ 52.9 × 0.375 × (18.4 - t)] = -365.01 + 19.8375t

Heat gained by water = 100 × 4.186 × 3.4 = 1423.24

Equating heat lost by brass to heat gained by water

-365.01 + 19.8375t = 1423.24

19.8375t = 1423.24 + 365.01

19.8375t = 1788.25

t = 90.1° C

Therefore, the initial temperature of the brass sample is 90.1°C

An unknown compound's 2,4-DNP product melting range is between 144-146'C. It does not give a silver mirror on the Tollens test and is slow to react to the chromic acid test. What would this compound be

Answers

Answer:

An unknown compound's 2,4-DNP product melting range is between 144-146'C. It does not give a silver mirror on the Tollens test and is slow to react to the chromic acid test. What would this compound be

Explanation:

From the given data it is clear that the unknown compound gives positive test with 2,4-DNP reagent.

That means it has a carbonyl group.Either aldehyde or ketone.

It does not give a silver mirror on the Tollens test and is slow to react to the chromic acid test.

That means aldehyde is absent.

So, the other carbonyl group that is ketone is present in the given unknown compound.

what does LPG stand for? mention one important source of LPG give sort answer​

Answers

Answer:

liquefied petroleum gas

LPG is prepared by refining natural gas. it is made by refining crude oil or from extracted natural gas streams as they emerge from the ground.

Which statement is true about molarity and percent by mass? (3 points)
They have the same unit.
They are inversely related.
They are different units of dilution.
They are different units of concentration.

Answers

Answer:

The guy above used photoshop here is the actual answer.

Explanation:

The true statements about molarity and percent by mass is that they are the different units of concentration

What is concentration?

Concentration of any substance present in any solution guves idea about their relative amount in that and it can de described in terms of molarity and percent by mass.

Molarity is define as the moles of solute present in per unit volume of the solution and has a unit of mol/L.Percent by mass is define as the mass of solute present in total mass of solution and it is a unit less quantity.They both gives idea about the concentration, not of the dillutions.They are not inversely related else they are directly related to each other as they are depends on the moles or mass of solute.

Hence, molarity and percent by mass are the different units of concentration and directly related to each other.

To know more about molarity & percent mass, visit the below link:

https://brainly.com/question/26150306

if salt and sand is mixed with distilled water, what will be the residue and what will be the filtrate?

Answers

Answer:

salt and sand

Explanation:it is what it is

A. Directions:Describe ways on how to protect humans and plants and animals Choose your answer in the box and fill in the concept map below​

Answers

Answer:

i) Humans - drinks lot of water

- use umbrella

- use hats and sunglasses

- apply sunblock when swimming

- wear rush guard

ii) Plants - water the plants

-put a shade on the plants

iii) Animals - provide pets with plenty of water

- place the animals under the tree during noon time

Which probing question lies within the scope of physics?
O A.
Are fish in the open ocean
attracted by underwater sounds?
O B.
Does increasing the saltiness of
ocean water affect the speed
of sound in the water?
O C.
What effect does the release of industrial wastewater have on
the acidity of oceans?
D. What is the effect of rising sea temperatures on
ocean currents?

Answers

Answer:

answer number C is the correct answer for this

The Li2+ ion is very similar to the hydrogen atom, in that it has one electron and energy levels similar
to the hydrogen atom. However, the relation = − (
1

2 −
1

2) cannot be used for this ion but
rather the relation = −2+ (
1

2 −
1

2) where the constant 2+=1.96x10-17J.
Use this relation to determine the third ionization energy, which is energy required to remove the last
electron from a Li2+ ion in kJ/mol, if the ion starts off in the ground state (Li2+ → Li3+
+ e-
).

Answers

Hhhhccffdfgcfghbvvbh

In a classroom, students who are biochemistry majors are learning about the overall organization of biological membranes. However, one of the students finds a WRONG explanation about the fluid mosaic model from a website and bring it up in a discussion. Which of the following is a WRONG explanation?

a. An explanation of the two-dimensional solutions of oriented lipids and globular proteins.
b. The lipid bilayer is a solvent for integral membrane proteins.
c. All membrane proteins diffuse laterally and freely in the lipid matrix.
d. None of the answers is correct.
e. The lipid bilayer is a permeability barrier for integral membrane proteins.

Answers

Answer:

e. The lipid bilayer is a permeability barrier for integral membrane proteins.

Explanation:

Integral membrane proteins enter the lipid bilayer by translocon channel which gives nascent polypeptide segment a chance to partition itself into lipid bilayer hydrophobic core.

How many g of Al are required to produce 2.8 mol of Al2O3

Answers

Answer:

290 g Al₂O₃

General Formulas and Concepts:

Atomic Structure

Reading a Periodic TableMoles

Stoichiometry

Using Dimensional Analysis

Explanation:

Step 1: Define

[Given] 2.8 mol Al₂O₃

[Solve] g Al₂O₃

Step 2: Identify Conversions

[PT] Molar Mass of Al: 26.98 g/mol

[PT] Molar Mass of O: 16.00 g/mol

Molar Mass of Al₂O₃: 2(26.98) + 3(16.00) = 101.96 g/mol

Step 3: Convert

[DA] Set up:                                                                                                       [tex]\displaystyle 2.8 \ mol \ Al_2O_3(\frac{101.96 \ g \ Al_2O_3}{1 \ mol \ Al_2O_3})[/tex][DA] Multiply [Cancel out units]:                                                                      [tex]\displaystyle 285.488 \ g \ Al_2O_3[/tex]

Step 4: Check

Follow sig fig rules and round. We are given 2 sig figs.

285.488 g Al₂O₃ ≈ 290 g Al₂O₃

Topic: AP Chemistry

Unit: Atomic Structure

290 g is the answer yeaaaa

a laser emits light with a frequency of 4.69 x 10 to the 14th power s - 1 calculate the wavelength of this light.

Answers

Answer:

6.40x10^-7

Explanation:

answer with work is attached.

The energy levels of hydrogenlike one-electron ions of atomic number Z differ from those of hydrogen by a factor of Z^2. Predict the wavelength of the 2s--->1s transition in He+.

Answers

Answer:

[tex]\mathbf{\lambda \simeq 3.039 \times 10^{-8} \ m}[/tex]

Explanation:

For a hydrogen-like atom, the spectral line wavelength can be computed by using the formula:

[tex]\bar v = Z^2 R_H \Big(\dfrac{1}{n_f^2}-\dfrac{1}{n_i^2}\Big)[/tex]

where:

emitted radiation of the wavenumber  [tex]\bar v[/tex] = ???

atomic no of helium Z = 2

Rydberg's constant [tex]R_H = 1.097*10^7 \ m^{-1}[/tex]

the initial energy of  the principal quantum [tex]n_1[/tex] = 2

the initial energy of  the principal quantum [tex]n_1[/tex] = 2

Now, the emitted radiation of the wavenumber can be computed as:

[tex]\bar v = (2)^2 (1.097*10^7 \ m^{-1} ) \Big(\dfrac{1}{1^2}-\dfrac{1}{2^2}\Big)[/tex]

[tex]\bar v = 3.291 \times 10^ 7/m[/tex]

Now, the wavelength for the transition can be computed by using the relation between the wavelength λ and the emitted radiation of the wavenumber  [tex]\bar v[/tex], which is:

[tex]\bar v = \dfrac{1}{\lambda}[/tex]

[tex]\lambda = \dfrac{1}{\bar v}[/tex]

[tex]\lambda = \dfrac{1}{3.291 \times 10^{7}}\times \dfrac{m}{1}[/tex]

[tex]\mathbf{\lambda =3.03859 \times 10^{-8} \ m}[/tex]

[tex]\mathbf{\lambda \simeq 3.039 \times 10^{-8} \ m}[/tex]

A calorimeter has been filled with 75 mL of water. The density of water at 25 °C is
0.998 g/mL. How many grams of water do you have at 25°C?

Answers

Answer:

isn't it 0.998

Explanation:

cause 0.998 is in the same grams / mole. I don't get

A calorimeter has been filled with 75 mL of water. The number of grams of water is 74.85 grams.

What is a calorimeter?

A calorimeter is an instrument that is used to measure calorimetry. It is used to measure the heat of chemical reactions and physical and chemical changes.

Mass is the quantity of matter in a physical body. Volume is the space occupied by a three-dimensional object. Mass is the quantity of matter in a physical body. The product of the compound's molar mass and the substance's moles are defined as mass.

Given, that the volume of the water is 75 mL

The temperature of the water is 25 °C

The density of water is 0.998 g/mL

To calculate the mass, the volume is multiplied by density.

Mass = volume x density

putting the values in the formula

75 x  0.998 = 74.85 grams

Thus, the grams of water that have at 25°C is 74.85 grams.

To learn more about density, refer to the link:

https://brainly.com/question/26304205

#SPJ2

A molecule contains hydrogen bonding if it contains hydrogen covalently bonded to Group of answer choices sulfur, oxygen, or fluorine. oxygen or nitrogen. fluorine, oxygen, or nitrogen. nitrogen, fluorine, oxygen, or nitrogen. chlorine, fluorine, or iodine.

Answers

Answer: A molecule contains hydrogen bonding if it contains hydrogen covalently bonded to (fluorine, oxygen, or nitrogen)

Explanation:

A hydrogen bond is a strong dipole-dipole attraction which occurs between

--> the hydrogen atom attached to a strongly electronegative atom, and

--> another strongly electronegative atom with a lone pair of electrons.

When an electronegative atom such as fluorine, oxygen or Nitrogen is bonded to hydrogen, a dipole develops causing the hydrogen to be partially negative. The electrostatic attraction between the partially positive hydrogen atom in one molecule and the partially negative atom of the more electronegative element in another molecule gives rise to the strong dipole-dipole attraction called hydrogen bonding.

Hydrogen fluoride, water and ammonia contain the three most electronegative elements, fluorine, oxygen and nitrogen respectively, linked directly to hydrogen. In addition, lone pairs of electrons are present in the fluorine, oxygen and nitrogen atoms of the three hydrides, making hydrogen bonds to form easily between them. These compounds which exhibits hydrogen bonding always have higher melting and boiling points.

Which of the following was NOT explained by Dalton's atomic theory?
ANSWER:
A. the Law of Multiple Proportions
B. the difference between elements and compounds
C.?the difference between isotopes of an element
D. the Law of Conservation of Mass

Answers

Answer:

i think 1. law of muliple proportion

Explanation:

please like

For which of the following transitions would a hydrogen atom absorb a photon with the longest wavelength?

a. n = 1 to n = 2
b. n = 3 to n = 2
c. n = 5 to n = 6
d. n = 7 to n = 6

Answers

Answer:

Hence among the options a and c, option d is that the correct answer because it has rock bottom energy ( as n value increases, energy decreases as energy levels come closer).

Explanation:

The relation between energy and wavelength is:

[tex]\Lambda = hC/E[/tex]  

From this equation, it's clear that wavelength and energy are inversely proportional to every other. The Lower the energy of a specific transition, the longest will the wavelength be of that specific transition.  

Among the given options, options b and d are often ruled out, since those transitions produce to release of a photon because it is coming down from an excited state.

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