The level of a liquid (i.e. distilled water) in laboratory glassware is determined by sight. The level corresponds to a specific volume. The volume is established by identifying the meniscus of the liquid relative to a calibration mark or series of calibration marks on the glassware (i.e. volumetric flask vs. buret). Which of the following statements is NOT correct when reading the meniscus?

a. the edge of the meniscus should be used to determine volume relative to the mark or marks
b. the meniscus should be read at eye level
c. when the meniscus is between marks, estimate the reading to the nearest tenth of a division (ie, estimate to 0.01 mL if buret has 0.1 ml divisions)
d. the center of the meniscus should be used to determine volume relative to the mark or marks

Answer:

C8H16O4

Explanation:

C2H4O= 24+4+16

44

n=molar mass/empirical formula

n=176.21/44

=4

Therefore

Molar Formula= (C2H4O)4=C8H16O4

Answer:

Formulas

3.2 Determining Empirical and Molecular Formulas

Learning Objectives

By the end of this section, you will be able to:

Compute the percent composition of a compound

Determine the empirical formula of a compound

Determine the molecular formula of a compound

The previous section discussed the relationship between the bulk mass of a substance and the number of atoms or molecules it contains (moles). Given the chemical formula of the substance, one may determine the amount of the substance (moles) from its mass, and vice versa. But what if the chemical formula of a substance is unknown? In this section, these same principles will be applied to derive the chemical formulas of unknown substances from experimental mass measurements.

Percent Composition

The elemental makeup of a compound defines its chemical identity, and chemical formulas are the most succinct way of representing this elemental makeup. When a compound’s formula is unknown, measuring the mass of each of its constituent elements is often the first step in the process of determining the formula experimentally. The results of these measurements permit the calculation of the compound’s percent composition, defined as the percentage by mass of each element in the compound. For example, consider a gaseous compound composed solely of carbon and hydrogen. The percent composition of this compound could be represented as follows:

%H=mass Hmass compound×100%

%C=mass Cmass compound×100%

If analysis of a 10.0-g sample of this gas showed it to contain 2.5 g H and 7.5 g C, the percent composition would be calculated to be 25% H and 75% C:

%H=2.5g H10.0g compound×100%=25%

%C=7.5g C10.0g compound×100%=75%

EXAMPLE 3.9

Calculation of Percent Composition

Analysis of a 12.04-g sample of a liquid compound composed of carbon, hydrogen, and nitrogen showed it to contain 7.34 g C, 1.85 g H, and 2.85 g N. What is the percent composition of this compound?

Solution

To calculate percent composition, divide the experimentally derived mass of each element by the overall mass of the compound, and then convert to a percentage:

%C=7.34g C12.04g compound×100%=61.0%%H=1.85g H12.04g compound×100%=15.4%%N=2.85g N12.04g compound×100%=23.7%

The analysis results indicate that the compound is 61.0% C, 15.4% H, and 23.7% N by mass.

Check Your Learning

A 24.81-g sample of a gaseous compound containing only carbon, oxygen, and chlorine is determined to contain 3.01 g C, 4.00 g O, and 17.81 g Cl. What is this compound’s percent composition?

ANSWER:

12.1% C, 16.1% O, 71.8% Cl

Determining Percent Composition from Molecular or Empirical Formulas

Percent composition is also useful for evaluating the relative abundance of a given element in different compounds of known formulas. As one example, consider the common nitrogen-containing fertilizers ammonia (NH3), ammonium nitrate (NH4NO3), and urea (CH4N2O). The element nitrogen is the active ingredient for agricultural purposes, so the mass percentage of nitrogen in the compound is a practical and economic concern for consumers choosing among these fertilizers. For these sorts of applications, the percent composition of a compound is easily derived from its formula mass and the atomic masses of its constituent elements. A molecule of NH3 contains one N atom weighing 14.01 amu and three H atoms weighing a total of (3 × 1.008 amu) = 3.024 amu. The formula mass of ammonia is therefore (14.01 amu + 3.024 amu) = 17.03 amu, and its percent composition is:

%N=14.01amu N17.03amuNH3×100%=82.27%%H=3.024amu H17.03amuNH3×100%=17.76%

This same approach may be taken considering a pair of molecules, a dozen molecules, or a mole of molecules, etc. The latter amount is most convenient and would simply involve the use of molar masses instead of atomic and formula masses, as demonstrated Example 3.10. As long as the molecular or empirical formula of the compound in question is known, the percent composition may be derived from the atomic or molar masses of the

The molar concentration, often called molarity, describes how much of a substance (a solute) is present per unit of solvent. By definition, the molar concentration (M) is equal to the number of moles (n) of solute divided by the number of liters (the volume, or V) of the solution.

Here, your solute is potassium nitrate, or KNO3. You're given the mass of KNO3 (505 g), but you need to convert this quantity to moles before you can find the molarity. To go from mass to moles, simply divide the mass of the substance by its molar mass (given to you as 101.1 g/mol).

[tex]505 \text{ g KNO}_\text{3} \div 101.1 \text{ g KNO}_3/\text{mol KNO}_{3} = 4.995 \text{ mol KNO}_3[/tex]

Now that we have the moles of solute, we divide by the liters of solution. We're given the volume of solution in milliliters, so to convert to liters, simply divide by 1000 (1 L = 1000 mL, so 1 mL = 1/1000 mL). Our volume of solution is thus 0.250 L.

Finally, we can calculate the molar concentration of the KNO3 solution:

[tex]4.995 \text{ mol KNO}_{3 }\div 0.250 \text{ L} = 19.98 \text{ }\frac{\text{moles}}{\text{liters}}\text{ of KNO}_3[/tex]

But, we're told to round our answer to three sig figs. Thus, our rounded and final answer would be 20.0 moles/liters of KNO3.

Answer:

[tex]m_{leftover}=37g[/tex]

Explanation:

Hello!

In this case, since the melting process involves the heat added to the system, the heat of fusion and the mass of water:

[tex]Q=m\Delta H_{fus}[/tex]

Thus, as it has been reported that the heat of fusion of ice is 333.6 J/g, we can compute the melted mass of ice as shown below:

[tex]m=\frac{Q}{\Delta H_{fus}} =\frac{46000J}{333.6J/g}\\\\m=138g[/tex]

Thus, the ice leftover results:

[tex]m_{leftover}=175g-138g\\\\m_{leftover}=37g[/tex]

Regards!

Answer:

1.01 grams/ cm^3

Explanation:

because that's just how it is

Answer:

Here it is (sorry its late)

Explanation:

The empirical and  molecular formula : C₂₁H₂₂N₂O₂

Given

The percent composition of an unknown substance is 75.42% Carbon, 6.63 % Hydrogen, 8.38 % Nitrogen, and 9.57 % Oxygen

Required

The empirical and  molecular formula

Solution

C : 75.42 : 12 = 6.285

H : 6.63 : 1 = 6.63

N : 8.38 : 14 = 0.599

O : 9.57 : 16 = 0.598

Divide by 0.598

C : H : N : O = 10.5 : 11 : 1 : 1 = 21 : 22 : 2 : 2

The empirical formula : C₂₁H₂₂N₂O₂

(C₂₁H₂₂N₂O₂)n = 334

(334)n=334

n = 1

Answer:

A) { + } Ge-Se { -}

B) { + } Ge-Br { - }

C) { - } Br-Se { + }

Explanation:

The (-)ive sign shall be placed for the atom with higher electronegativity, while the other atom will be electropositive.  

a) Electronegativity of Ge = 2.01

Electronegativity of Se = 2.55

{ + } Ge-Se { -}

b) Electronegativity of Ge = 2.01

Electronegativity of Br = 2.95

{ + } Ge-Br { - }

c) Electronegativity of Br = 2.95

Electronegativity of Se = 2.55

{ - } Br-Se { + }

Answer:

The answer is "Strontium iodide and [tex]SrI_2[/tex]".

Explanation:

In the flames test, two ionic metals give red fire. It was calcium (Ca, which gives a red brick flame) and strontium (Sr, which gives a persistent red flame). Both Ca and Sr respond to insoluble carbonate with ammonium carbonate. Ca and Sr produce insoluble ammonium phosphate phosphates. Even then, the water is reactive with calcium sulfate (CaSO4) whereas the strontium sulfate (SrSO4) is illiquid. Because the metal ion formed 3 precipitates, they can't get Ca, and we have Sr as its metal.

The hexane of its halide gives a violet color which would be typical of iodide (I-).

Strontium iodide is the chemical name of the unknown ionic compound.

Strontium iodide's chemical formula is [tex]SrI_2[/tex].

Answer:

what is that's a question

According to specific heat capacity, 13.09 grams of water at 0 degree Celsius  can be frozen into ice at zero degree c if 55 kJ of heat is removed.

Specific heat capacity is defined as the amount of energy required to raise the temperature of one gram of substance by one degree Celsius. It has units of calories or joules per gram per degree Celsius.

It varies with temperature and is different for each state of matter. Water in the liquid form has the highest specific heat capacity among all common substances .Specific heat capacity of a substance is infinite as it undergoes phase transition ,it is highest for gases and can rise if the gas is allowed to expand.

It is given by the formula ,

Q=mcΔT, substitution in formula gives Q/c=m which is m= 55/4.2=13.09 grams.

Thus, 13.09 grams of water at 0 degree Celsius  can be frozen into ice at zero degree c if 55 kJ of heat is removed.

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#SPJ2

[tex]\tt -\dfrac{1}{2}\dfrac{d[N_2O]}{dt}=\dfrac{1}{2}\dfrac{d[N_2]}{dt}=\dfrac{1}{1}\dfrac{d[O_2]}{dt}[/tex]

Reaction

2N2O(g) — 2N2(g) + O2(g)

Required

relative rate

Solution

The reaction rate (v) shows the change in the concentration of the substance (changes in addition to concentrations for reaction products or changes in concentration reduction for reactants) per unit time.

so the relative rates for the reaction above are :

[tex]\tt -\dfrac{1}{2}\dfrac{d[N_2O]}{dt}=\dfrac{1}{2}\dfrac{d[N_2]}{dt}=\dfrac{1}{1}\dfrac{d[O_2]}{dt}[/tex]

Answer:

Same bond angle-CO2, CH4, SF6, PCl5, BF3, BeF2, XeF4,XeF2

Different bond angle- H2O, SO2, NH3, ClF3,SF4

Explanation:

We know that the shape of molecules and and bond angles between atoms in molecules are predicted on the basis of the valence shell electron pair repulsion theory.

Most times, certain molecules deviate from the expected bond angles for different reasons. The most common reason is the presence of lone pairs on the molecule. This is the case in the molecules; H2O, SO2, NH3, ClF3 and SF4.

However, in XeF4 and XeF2, the lone pairs orient themselves in such a way that they do not distort the expected bond angle. For instance, in XeF2, the  three lone pairs occupy equatorial positions while the two bond pairs occupy apical positions. In XeF4, the bond pairs are directed at the corners of a square while the two lone pairs are positioned above and below the plane of the square.

Answer:

12408 feet per minute

Explanation:

Given: Speed is 141 mi/h

To find: speed in units of feet per minute

Solution:

Use the following units to convert the given speed into feet per minute.

1 mile = 5280 foot

1 h = 60 minutes

Therefore,

141 mi/h [tex]=\frac{141(5280)}{60} =12408[/tex] feet per minute.

The boiling point of water generally increases as the amount of impurities (which a solute like KCl technically can be thought of) dissolved increases. This relation can be quantified using the equation,

[tex]\Delta T_b = i \times K_b \times m[/tex]

where [tex]\Delta{T}_{b}[/tex] is the change in the water's boiling point (normally taken to be 100 °C), [tex]i[/tex] is the Van 't Hoff factor (the number of particles a single formula unit of the solute dissociates into in water), [tex]K_b[/tex] is the boiling point elevation constant, and [tex]m[/tex] is the molality (moles of solute/kilogram(s) of solvent) of the solution.

We are forming a solution by dissolving KCl in water. KCl is an electrolyte that, in water, will dissociate into K⁺ and Cl⁻ ions. So, for every formula unit, KCl, we obtain two particles. Thus, the Van 't Hoff factor, or [tex]i[/tex], will be 2.

The molality of the solution can be calculated by dividing the number of moles of KCl by the mass of water in kilograms. Since we have 1.00 kg of water, we would be dividing 0.75 mol KCl by 1, giving us a molality (m) of 0.75 m.

We aren't provided the boiling point elevation constant for water. Several authoritative sources give the value 0.512 °C/m, so we will adopt that as our [tex]K_b[/tex].

Note: m = mol/kg as used in this problem.

Plugging everything in,

[tex]\Delta T_b = i \times K_b \times m \\\Delta T_b = 2 \times 0.512 \text{ } \frac{^oC}{mol/kg} \times 0.75 \text{ } \frac{mol}{kg} \\\Delta T_b = 0.768 \text{ } \mathrm{ ^oC}[/tex]

As you can see, our change in boiling point is positive (the boiling point is elevated), and it is also quite modest. Taking 100 °C to be the boiling point of pure water, the boiling point of our solution would be 100 ⁰C + 0.768 ⁰C, or 100.768 ⁰C.

If we are considering significant figures, then we must give our answer to two significant figures (since 0.75 has two sig figs). We can regard the boiling point of water (100 ⁰C) as a defined value. Since our final answer is a sum, the boiling point of our solution to two significant figures would be 100.77 ⁰C.

Given:

We know,

The molality of the solution will be:

= [tex]\frac{Mole}{Mass}[/tex]

= [tex]\frac{0.75}{1}[/tex]

= [tex]0.75 \ m[/tex]

Now,

→ [tex]T_{solution}-T_{water} = Kb\times m\times i[/tex]

By putting the values, we get

                              [tex]= 0.51\times 0.75\times 2[/tex]

                              [tex]= 0.765[/tex]

hence,

Solution's boiling point will be:

→ [tex]T_{solution} = 100+0.765[/tex]

                [tex]= 100.765^{\circ} C[/tex]

Thus the above approach is right.

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Answer:

Electrons in a hydrogen atom must be in one of the allowed energy levels. If an electron is in the first energy level, it must have exactly -13.6 eV of energy.

...

Energy Levels of Electrons.

Energy Level Energy

1 -13.6 eV

2 -3.4 eV

3 -1.51 eV

4 -.85 eV

Answer:

m = 1.0164 g

% = 65.03%

Explanation:

First of all, we need to write the chemical reaction that is taking place here. We have the camphor being reduced to isoborneol:

C₁₀H₁₆O + NaBH₄ -----------> C₁₀H₁₈O + NaBH₂

We have a 1:1 mole ratio between Camphor and isoborneol, so, the moles of the camphor will be the same moles produced of isoborneol.

To get the theorical yield we need to calculate the theorical moles produced of isoborneol, then, the mass and compare it to the given mass. In that way we will get the %yield.

The Molar mass of camphor and isoborneol are:

MM C₁₀H₁₆O = (16*1) + (12*10) + 16 = 152 g/mol

MM C₁₀H₁₈O = (18*1) + (12*10) + 16 = 154 g/mol

The moles of camphor will be:

molesC₁₀H₁₆O = 1 / 152 = 0.0066 moles

The mass produced then of isoborneol should be:

mC₁₀H₁₈O = 0.0066 * 154

Now, the %yield would be:

% = (0.661 / 1.0164) * 100

Hope this helps

Answer:

1 product is made. The left overs are 1 piece of bread and 1 slice of cheese

Explanation:

Answer:

Moles of carbon atoms  = 3.33  ×  [tex]10^{-6}[/tex] mol

No. of atoms of C in Diamond  = 2.007 ×   [tex]10^{28}[/tex] atom

Atoms of graphite = 6.27 × [tex]10^{23}[/tex] Atoms

Explanation:

given data

Cost of 0.2g of diamond = $5000

Cost of 25 g of graphite = $ 2

solution

we know cost of 0.2g of diamond is $ 5000 so that for 1$

if buy 1$ = [tex]\frac{0.20}{5000}[/tex]

1$ = 4.0 × [tex]10^{-5}[/tex] g Carbon

and Moles of carbon atoms  is express as

Moles of carbon atoms = Given mass of Carbon ÷ atomic mass of C      .........1

Moles of carbon atoms  = 4.0  ×  [tex]10^{-5}[/tex]    g/ 2.0g

Moles of carbon atoms  = 3.33  ×  [tex]10^{-6}[/tex] mol

and

No. of atoms of C in Diamond = No. of moles × Avogadro NO    ..............2

No. of atoms of C in Diamond  = 3.33 ×   [tex]10^{-6}[/tex] mol × 6.022 ×   [tex]10^{28}[/tex]

No. of atoms of C in Diamond  = 2.007 ×   [tex]10^{28}[/tex] atom

Graphite

and wew have given Cost of 25 g of graphite is $2 so for but 1$ we get

for buy $1 = 25÷2  = 12.5 g Of graphite

Moles of graphite = 12.5÷12 = 1.04 mol

Atoms of graphite = 1.04 × 6.022 × 1023

Atoms of graphite = 6.27 × [tex]10^{23}[/tex] Atoms

Answer:

3 H1 NMR signals

Explanation:

NB: kindly check the diagram of the chemical compound in the attached picture.

This particular Question is based on the part of chemistry which is known as spectroscopy. Spectroscopy is used in the Determination or in identifying chemical compounds. H'NMR works on the principle of nuclear magnetic resonance.

In order to solve this question, one has to count the number of hydrogen in unique location. The diagram in the attached show how hydrogen is been counted.

The numbers of signals is the number of different chemical environments in which hydrogen atoms are located.

NB: signals is also the same as peak in H'NMR.

Hence, the number of H1 NMR signals in this chemical compound is 3.

Answer:

BrO3

Explanation:

The empirical formula is the smallest whole-number ratio, you find the greatest common factor (which is 2, in this case), then divide the subscripts by it.

So:

Br2 / 2 = Br1

O6 / 2 = O3

Answer:

Love for Music

Explanation:

This is one example of many non-physical traits. In the womb a mother can listen to her favorite music and the growing baby could grow to like it in the womb!

This is just one of the many other traits that could be passed to their offspring.

Hope this Helps!

Here, we are required to determine what types of atoms are present in the simplest chemical substance.

Chemical substances are generally classified as either;

Definition of terms;

Elements and Compounds are collectively termed Pure Substances.

Therefore, inference drawn from the premises above point to the fact that the simplest chemical substances are composed of the atoms of one type of element.

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Answer:

it develops from the womb

Answer:

outer cells of the blastocyst

Explanation:

on edg:)

[tex]{ \boxed{ \bold{ \blue{Question}}}}[/tex]

Is H2SO4 an element, compound or molecule?

[tex]{ \boxed{ \bold{ \blue{Answer}}}}[/tex]

H2SO4 (sulphuric acid) is a compound. It is made up of 2 hydrogen atoms, 1 sulphur atom, and 4 oxygen atoms.

_______________________________

[tex] \underline \bold \orange{hope \: it \: helps}[/tex]

A chemical compound is any substance that consists of two or more different elements combined together.

I think that H2SO4 fits this definition of a compound .

HOPE IT HELPS

PLEASE MARK ME BRAINLIEST ☺️

Answer:

SnCl4 * 5H2O

Explanation:

Answer: i think its A diatomic compound..

Explanation: hope i helped! sorry if im wrong!