During a titration, the solution with the unknown concentration is called the _____.

Answer:

The answer is A

Explanation:

When nH2/nO2 =3/4 => it can cause explosion

Answer:

Explanation:

Precision relates to instruments of measurement or scale . A scale measuring upto cm is less precise than an instrument measuring upto mm .

Here the first measurement appears to have been taken with an instrument measuring up to metre and the second measurement appears to have been taken with an instrument measuring up to decimeter . So second measurement is most precise .

Third measurement is closest to the actual measurement that is 45.0 m , so it is most accurate measurement .

Answer:

a. 3-methylbutan-2-ol

b. 2-methylcyclohexan-1-ol

Explanation:

For this reaction, we must remember that the hydroboration is an "anti-Markovnikov" reaction. This means that the "OH" will be added at the least substituted carbon of the double bond.

In the case of 2-methyl-2-butene, the double bond is between carbons 2 and 3. Carbon 2 has two bonds with two methyls and carbon 3 is attached to 1 carbon. Therefore the "OH" will be added to carbon three producing 3-methylbutan-2-ol.

For 1-methylcyclohexene, the double bond is between carbons 1 and 2. Carbon 1 is attached to two carbons (carbons 6 and 7) and carbon 2 is attached to one carbon (carbon 3). Therefore the "OH" will be added to carbon 2 producing 2-methylcyclohexan-1-ol.

See figure 1

I hope it helps!

Answer:

e. 1.4.

Explanation:

Hello,

In this case, for a second-order reaction, the integrated rate law is:

[tex]\frac{1}{[A]} =kt+\frac{1}{[A]_0}[/tex]

In such a way, for the given data, we compute the initial concentration as shown below in molar units (M):

[tex]\frac{1}{[A]_0} =\frac{1}{[A]}-kt=\frac{1}{0.65M} -\frac{0.025}{M*s}*33s \\\\\frac{1}{[A]_0} =\frac{0.713}{M}[/tex]

[tex][A]_0=\frac{1M}{0.713} =1.4M[/tex]

Therefore, answer is e. 1.4 M.

Regards.

The initial concentration of the reaction is 1.4 M.

Using the formula;

1/[A] = kt + 1/[A]o

Where;

[A] = concentration at time t =  0.65 M

t = time = 33 s

k = rate constant = 0.025 M-1s-1

[A]o = initial concentration = 0.025 M-1s-1

Hence;

1/ 0.65 = (0.025 × 33) +  1/[A]o

1/[A]o = (0.65)^-1 -  (0.025 × 33)

1/[A]o = 1.54 - 0.83

[A]o = 1.4 M

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Answer:

X 86 206

Explanation:

Radioactive atoms are nuclei that can under go disintegration to emit either an alpha particle, beta particle or gamma radiation. The process could be spontaneous or stimulated.

When a radioactive atom R 88 210 emits alpha particle, it would produce an element with atomic number 86 and mass number 206 i.e X 86 206. An alpha particle is usually a helium nucleus.

                     [tex]R^{210}[/tex] ⇒ [tex]x^{206}[/tex] + [tex]He^{4}[/tex] + energy

Answer:

Final temperature = 100°C

Explanation:

The general equation of a coffee cup calorimeter is:

Q = m×C×ΔT

Where Q is the heat added to the system (3.6kJ = 3600J), m is the mass of the substance (200.0g), C is specific heat (0.240J /g°C) and ΔT is change in temperature).

Computing the values:

3600J = 200.0g×0.240J/(g°C)×ΔT

75°C = ΔT

ΔT is the difference in temperature between final and initial temperature. As intital temperature was 25°C:

75°C = Final T - 25°C

Answer:

hydrogen chloride (HC)- insoluble in hexane

hydrogen sulfide (H2S)- insoluble in hexane

water (H2O)- insoluble in hexane

propane (CH3CH2CH3)- soluble in hexane

Explanation:

Generally, it is a principle in chemistry that polar solvents dissolve polar substances while nonpolar solvents dissolve nonpolar substances.

This is because, dissolution of a substance in another substance depends on the kind of intermolecular interaction that is possible between the two substances. Hence, ionic substance dissolve in polar solvents due to dipole interactions and nonpolar substances dissolve in nonpolar solvents due to Vanderwaals interaction between the solute and solvent.

Hydrogen chloride, hydrogen sulphide and water are ionic substances hence they can not dissolve in hexane which is a nonpolar substance. However, propane is a nonpolar solvent hence it dissolves in hexane.

Answer: butane (CH3CH2CH2CH3) soluble

hydrogen chloride ( HCl) insoluble

hydrogen sulfide (H_2S) insoluble

water (H_2O) insoluble

Answer:enamel is formed by differentiated dental epithelial cells known as ameloblasts.

Explanation:

Answer:

[tex]\large \boxed{\mathrm{subscripts}}[/tex]

Explanation:

Subscripts are numbers written after elements, subscripts indicate how many of each atom there are in a compound.

The atoms of each element in an compund is written in the subscript. The number of atoms present in any compound whether made up of only same element or different element is termed as Atomicity.

Given compound = [tex]\boxed{\sf{H_2O}}[/tex]

Here, there are two atoms of hydrogen and one atom of oxygen, So ratio of the atoms of elements in Water molecule = 2 : 1

━━━━━━━━━━━━━━━━━━━━

Answer:

3.83 mol/ L

Explanation:

Molarity is the amount of moles of a substance in a liter of solution.

1.8L ----- 6.9 mol of KCl

1L ----- 6.9 ÷1.8= 3.83 moles of KCl (3 s.f.)

Thus the molarity is 3.83 mol/L.

Answer: 3.8

Explanation:

Original answer is 3.83 but it needs significant figures so you need to round it to 2 significant figures

Answer:

1. 33.43 g of KCl

2. 23.70 g of KBr

3. 50.45 g of Cr₂O₃

4. 18.82 g of SrO

Explanation:

Molar mass of  the elements and compounds in each of the reactions:

K = 39.0 g, Cl = 35.5 g, KCl = 74.5 g, Br = 80.0 g, KBr = 119.0 g, Cr = 52.0 g, O = 16.0 g, Cr₂O₃ = 152.0 g, Sr = 88.0 g, SrO = 104.0 g

1) 2K(s)+Cl2(g)/15.93G→2KCl(s)

From the mole ratio of the reaction above, 2 moles of K reacts with 1 mole of Cl₂ to give 2 moles of KCl

78.0 g (2 * 39.0 g) of K reacts with 71.0 g (2*35.5) of Cl₂ to produce 149.0 g(2*74.5) of KCl, therefore, Cl₂ is the limiting reactant.

15.93 g of Cl₂ will react to produce (149/71) * 15.93 of KCl = 33.43 g of KCl

2) 2K(s)+Br2(l)/15.93→2KBr(s)

From the mole ratio of the reaction, 2 moles of K reacts with 1 mole of Br₂ to give 2 moles of KBr

78.0 g (2 * 39.0 g) of K reacts with 160.0 g (2*80) of Br₂ to produce 238.0 g(2*119.0) of KBr, therefore, K is the limiting reactant which though is in excess.

15.93 g of Br₂ will react to produce (238/160) * 15.93 of KBr = 23.70 g of KBr

3) 4Cr(s)+3O2(g)/15.93→2Cr2O3(s)

From the mole ratio of the reaction, 4 moles of Cr reacts with 3 moles of O₂ to give 2 moles of Cr₂O₃

208.0 g (4 * 52.0 g) of Cr reacts with 96.0 g (3*2*16) of O₂ to produce 304.0 g (2*152.0) of Cr₂O₃, therefore, O₂ is the limiting reactant.

15.93 g of O₂ will react to produce (304/96) * 15.93 of Cr₂O₃ = 50.45 g of Cr₂O₃

4) 2Sr(s)/15.93+O2(g)→2SrO(s)

From the mole ratio of the reaction, 2 moles of Sr reacts with 1 mole of O₂ to give 2 moles of SrO

176.0 g (2* 88.0 g) of Sr reacts with 32.0 g (2*16) of O₂ to produce 208.0 g (2*104.0) of SrO, therefore, O₂ is the limiting reactant which though is in excess.

15.93 g of Sr will react to produce (208/176) * 15.93 of SrO = 18.82 g of SrO

Answer:

d. 0.15 mol

Explanation:

Step 1: Given data

Step 2: Convert the mass of the solvent to kilograms

We will use the relationship 1 kg = 1,000 g.

66.6 g × (1 kg/1,000 g) = 0.0666 kg

Step 3: Calculate the moles of solute

The molality is equal to the moles of solute divided by the kilograms of solvent.

m = moles of solute / kilograms of solvent

moles of solute = m × kilograms of solvent

moles of solute = 2.4 mol/kg × 0.0666 kg

moles of solute = 0.15 mol

Answer:

salt in the Dead Sea is sodium chloride

while salt in the lab is either soluble or

insoluble in water.

Explanation:

The term 'salt' in the school laboratory does not always refer to sodium chloride. It is a generic term used for many substances especially those substances formed by neutralization reaction.

There are many salts that are used in the laboratory. Some of these salts are soluble in water while some are not soluble in water.

Salt in the dead sea always refers to sodium chloride, hence, salt in the dead sea is different from salt in the school laboratory.

Answer:

6 mol/min

Explanation:

2A+2B→4C

The relationship between the reactants and products of this equation is given by;

1/2 -d[A]/dt = 1/2 -d[B]/dt = 1/4 d[C]/dt

Our focus is on A and C

From the question;

d[A]/dt = 3mol/min

We have;

1/2 (3) = 1/4 d[C]/dt

d[C]/dt = 4/2 * 3 = 6 mol/min

Answer:

True

Explanation:

Answer:

Hypothesis: High school graduation rate does not have an effect on the rate of crime in the society

Independent variable: Rate of high school graduation

Dependent variable: crime

Existing data: Crime data/reports (for the duration of interest) from different (randomized) police stations and the High school graduation rate data/information (for the same duration of interest) from the schools in the same jurisdictions as the police stations.

Explanation:

1) Before conducting an experiment, a hypothesis has to be put forward. This  hypothesis is then proven or unproven by the outcome of the experiment. One of the best ways of proposing a hypothesis is the use of null hypothesis, which suggests that there is no significant difference or "connection" between two variables. Here, the null hypothesis can be "High school graduation rate does not have an effect on the rate of crime in the society"

2) An independent variable is a variable whose variation is not determined or thought to be determined by the change(s) in the other variable. Here, high school graduation rate is not determined or thought to be determined by the other variable.

3) A dependent variable is a variable whose variation is predicted to be as a result of the change(s) in the other variable. Here, the rate of crime is predicted to be as a result of the high school graduation rate

4) Existing/available data that can be used to examine the hypothesis proposed earlier can be obtained from the crime data/reports (for the duration of interest) from different (randomized) police stations and the High school graduation rate data/information (for the same duration of interest) from the schools in the same jurisdictions as the police stations.

Answer:

9 protons

Explanation:

An element's atomic number is equal to the amount of protons in the nucleus - otherwise, the element's chemical identity would be different and it would be a completely different element.

Referencing any periodic table, we notice that fluorine has the atomic number of 9.

Because the atomic number is the same as the number of protons in the nucleus, fluorine has 9 protons.

Answer:

Half-lives of first order reactions

Explanation:

Notice the the half-life is independent of initial concentration. This is not the case with other reaction orders. The half-life of a first-order reaction was found to be 10 min at a certain temperature. hope this helps you :)

0.0453 sec⁻¹  the rate constant of a first-order reaction when 20.0% of a reactant remains after 73.5 s.

The constant is indeed a proportional factor in chemical kinetics' rate equation that connects reactant molar concentration to reaction rate. It is additionally known as the pre - exponential factor or reaction rate factor and is represented by the symbol k in an equation.

The constant, k, is indeed a constant of proportionality that illustrates the connection between reactant molar concentration and reaction rate. Using the molar quantities of the reagents and the sequence of reaction, the constant may be determined experimentally. It may also be computed using the Following equations.

t1/2 = 0.693/k

Fraction remaining = 0.5n

n = number of half lives

0.20 = 0.5n

log 0.20 = n log 0.5

n = 2.32

2.32 half lives = 35.5 sec

1 half life = 15.3 sec

15.3 sec = 0.693/k

k = 0.0453 sec-1

Therefore, 0.0453 sec⁻¹  the rate constant of a first-order reaction when 20.0% of a reactant remains after 73.5 s.

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Answer:

c: is a good conductor of electricity

Explanation:

One of the physical properties of hydrochloric acid is that it is a good conductor of electricity in an aqueous state.

The dissolution of hydrochloric acid in water causes a complete dissociation into [tex]H^+[/tex] and [tex]Cl^-[/tex]. The free-floating ions that result from the dissolution enable hydrochloric acid to be able to conduct electricity.

In aqueous solution, the attraction of the positive dipole of the hydrochloric acid to the negative dipole of water and that of the positive dipole of water to the negative dipole of the hydrochloric acid creates a dipole-dipole interaction that allows complete dissociation of the hydrochloric acid. Thus, electrolyte results.

Correct option: c

Answer:

[tex]m_{MgCO_3}=0.0202molMgCO_3[/tex]

Explanation:

Hello,

In this case, for this purpose we first have to write the undergoing chemical reaction:

[tex]Na_2CO_3+Mg(NO_3)_2\rightarrow MgCO_3+2NaNO_3[/tex]

Thus, since the mole ratio between the reactants is 1:1, we next identify the limiting reactant by computing the available moles of sodium carbonate and those moles of the same reactant consumed by the magnesium nitrate considering the given solutions:

[tex]n_{Na_2CO_3}=0.010L*0.300\frac{molNa_2CO_3}{1L}=0.003molNa_2CO_3 \\\\n_{Na_2CO_3}^{consumed}=0.006L*0.0400\frac{molMg(NO_3)_2}{1L}*\frac{1molNa_2CO_3}{1molMg(NO_3)_2} =0.00024molNa_2CO_3[/tex]

In such a way, since less moles are consumed, we can say that the sodium carbonate is excess whereas the magnesium nitrate is the limiting one, therefore, the yielded mass of magnesium carbonate turns out:

[tex]m_{MgCO_3}=0.00024molMg(NO_3)_2*\frac{1molMgCO_3}{1molMg(NO_3)_2}*\frac{84.31gMgCO_3}{1molMgCO_3} \\\\m_{MgCO_3}=0.0202molMgCO_3[/tex]

Regards.

Answer:

- [tex]n_{etOH}=0.11mol\ et OH[/tex]

- [tex]atoms_C=1.0x10^{23} atoms\ C[/tex]

Explanation:

Hello,

In this case, since ethanol has a molar mass of 46 g/mol, the moles in 5.0 g are:

[tex]n_{etOH}=5.0g\ etOH*\frac{1mol\ etOH}{46 g\ etOH} =0.11mol\ et OH[/tex]

Moreover, since the formula of glucose is C₆H₁₂O₆, its molar mass is 180 g/mol and six moles of carbon are in one mole of glucose (based on carbon's subscript), the atoms are computed by using the 6:1 mole ratio and the Avogadro's number as shown below:

[tex]atoms_C=5.0gC_6H_{12}O_6*\frac{1molC_6H_{12}O_6}{180gC_6H_{12}O_6}*\frac{6molC}{1molC_6H_{12}O_6} *\frac{6.022x10^{23}atoms\ C}{1molC} \\\\atoms_C=1.0x10^{23} atoms\ C[/tex]

Regards.

Answer:

A neutralization of a strong acid by a strong base gave out 5590 J of heat energy.

Determine the enthalpy change (in kJ) for the reaction.

Explanation:

A strong acid being neutralized by a strong base releases 5590 J of heat energy.

A chemical reaction in which an acid and a base interact quantitatively is known as neutralization or neutralisation. By neutralizing a reaction in water, surplus hydrogen or hydroxide ions are removed from the solution.

Neutralization is a sort of chemical reaction in which an acid and a base combine to produce salt and water. For instance: Reaction of sodium hydroxide and hydrochloric acid (HCl) Sodium hydroxide reacts with hydrochloric acid to form their salt sodium chloride (NaCl) and water.

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Answer:

Be

Explanation:

[tex]^94Be + ^42He \rightarrow ^{12}6C + ^10x[/tex]

Therefore, the element symbols is Be, which when bombarded by an α particle, will generate carbon-12 and a neutron.

Answer:

8.0356 * 10^-5 moles of NaHCO3

Explanation:

Sulphuric acid = H2SO4

Sodium bicarbonate = NaHCO3

The reaction between both compounds is given by;

2NaHCO3(aq) + H2SO4(aq) → Na2SO4(aq) + 2CO2(g) + 2H2O(l)

In the reactin above;

2 mol of NaHCO3 neutralizes 1 mol of H2SO4

At stp, 1 mol occupies 22.4 L;

1 mol = 22.4 L = 22400 mL

x mol = 0.9 mL

x = 0.9 / 22400 = 4.0178 * 10^-5 moles of H2SO4

Since 2 mol = 1 mol from the equation;

x mol = 4.0178 * 10^-5

x mol = 2 * 4.0178 * 10^-5

x = 8.0356 * 10^-5 moles of NaHCO3

english please so i can help

Answer:

I believe the answer is a covalent bond

Answer:

the atom

Explanation:

The bread and cheese separately represent the atom because both bread and cheese are different from one another and we cannot assume it as a molecule because molecules formed when the group of atoms combine together by making bonds with each other and we know that bread and cheese did not make bonds with each other, they only attached, so we called them atoms not molecule.

Explanation: