Consider the heating curve for water. A graph of the heating curve for water has time in minutes on the horizontal axis and Temperature in degrees Celsius on the vertical axis. A line runs through the following points: 0 minutes, negative 20 degrees; 0.5 minutes, 0 degrees; 2 minutes, 0 degrees; 4 minutes, 100 degrees; 8 minutes, 100 degrees; 9.5 minutes, 160 degrees. At what temperature does the solid start melting? –20°C 0°C 20°C 80°C

Answer:

a. The rate of the reaction is not proportional to the concentration of the reactant.

Explanation:

The rate expression for a zero order reaction is given as;

A → Product

Rate = k[A]⁰

[A]⁰ = 1

Rate = K

GGoing through the options;

a) This is correct because in the final form of the rate expression, the rate is independent of the concentration.

b) This option is wrong

c) This option is also wrong

d) Like options b and c this is also wrong becaus ethere is no relationship between either the concentration or t.

Answer:

2.92 mol

Explanation:

Step 1: Write the balanced equation

2 B(s) + 6 HCI(aq) ⇒ 2 BCl₃(aq) + 3 H₂(g)

Step 2: Establish the appropriate molar ratio

The molar ratio of hydrochloric acid to boron chloride is 6:2.

Step 3: Calculate the moles of boron chloride produced from 8.752 moles of hydrochloric acid

[tex]8.752molHCl \times \frac{2molBCl_3}{6molHCl} = 2.92molBCl_3[/tex]

Answer:Mass of CO2 = 0.60g

Explanation:

Given the chemical rection

Li2CO3(s) + 2HCl(aq) --> 2LiCl(aq) + H2O(l) + CO2(g

No of moles = mass / molar mass

molar mass Li2CO3 = Molecular mass  calculation: 6.941 x 2 + 12.0107 + 15.9994 x 3 =  

= 73.8909 g/mol

therefore Number of moles Li2CO3 = 1.0g / 73.89 g/mol

= 0.0135 moles Li2CO3

From our given Balanced equation,  shows that  

Li2CO3(s) + 2HCl(aq) --> 2LiCl(aq) + H2O(l) + CO2(g

1 mole Li2CO3 produces 1 mole CO2

therefore 0.0135 mol Li2CO3 will produce  0.0135 moles of CO2

Also

No of moles = mass / molar mass

Mass = No of moles x molar mass

molar mass of CO2=12.0107 + 15.9994 x 2=44.0095 g/mol

Mass of CO2= 0.0135 X 44.0095 g/mol =0.594≈0.60g

Answer:

It was because the vaccine generated actively acquired immunity, that is, inoculation of a portion of the measles virus so that the body forms the antibodies for a second contact and thus can destroy it without triggering the pathology.

Explanation:

Vaccines are methods of active acquired immunity since the antibody is not passively inoculated, it is manufactured by the body with a physiological process once part of the virus is inoculated.

The measles virus most of all affected the lives of infants or newborn children with severe rashes and high fevers that led to death.

Answer: their amounts vary throughout the atmosphere

Explanation:

There is very little that travels over the atmosphere

Vary=very little

Hope that helps

Answer:

it's a two step elimination reaction

Explanation:

it follows a carbocationic pathway. When carbocation is stable, the equation is favourable, that is, double bond is formed by expelling hydrogen atom.

Answer:

The answer is A

Explanation:

Answer:

T = 48.39%

Explanation:

In this case we need to apply the Beer law which is the following:

A = CεL  (1)

Where:

A: Absorbance of solution

C: Concentration of solution

ε: Molar Absortivity (Constant)

L: Length of the cell

Now according to the given data, we have transmittance of 93% or 0.93. We can calculate absorbance using the following expression:

A = -logT (2)

Applying this expression, let's calculate the Absorbance:

A = -log(0.93)

A = 0.03152

Now that we have the absorbance, let's calculate the concentration of the solution, using expression (1).

A = CεL

C = A / εL

Replacing:

C = 0.03152 / 1 *ε   (3)

Now, we want to know the transmittance of the solution with a length of 10 cm. so:

A = CεL

Concentration and ε are constant, so:

A = (0.03152 / ε) * ε * 10

A = 0.3152

Now that we have the new absorbance, we can calculate the new transmittace:

T = 10^(-A)

T = 0.4839 ----> 48.39%

Answer:

0.129 M

Explanation:

0.100 M HCl = 0.100 mol/L solution HCl

5.00 mL = 0.00500 L solution HCl

0.100 mol/L HCl * 0.00500 L = 0.000500 mol HCl

                             HCl ------> H+ + Cl-

                           1 mol                   1 mol

                    0.000500 mol           0.000500 mol

0.200 M NaCl = 0.200 mol/L solution NaCl

2.00 mL = 0.00200 L solution NaCl

0.200 mol/L NaCl*0.00200 L = 0.000400 mol NaCl

                              NaCl ------> Na+ + Cl-

                            1 mol                        1 mol

                     0.000400 mol               0.000400 mol

Chloride ion altogether (0.000500 mol + 0.000400 mol) =0.000900 mol

Solution altogether (0.00500 L+0.00200 L) = 0.00700L

Molarity (Cl-)= solute/solution = 0.000900 mol/0.00700L = 0.129 mol/L=

= 0.129 M

Answer:

K = 150, C = - 123.15°

Explanation:

Kelvin = Celcius + 273.15 / 0 Kelvin = - 273.14 C

_____________________________________

Thus,

150 K = Celcius + 273.15,

150 - 273.15 = C,

C = -123.15 degrees

Solution, C = - 123.15°

Answer:

C=-123.15

Explanation:

This is easy

Answer:

D. rate = k [(CH3)3CCl]

Explanation:

(CH3)3CCl + OH- → (CH3)3COH + Cl-

The mechanisms are;

Step 1)

(CH3)3CCl → (CH3)3C+ + Cl- (slow)

Step 2)

(CH3)3C+ + OH- → (CH3)3COH (fast)

In kinetics, the slowest step is the ratee determining step.

For a given reaction;

A → B + C, the rate law expression is given as;

rate = k [A]

In this problem, from step 1. The rate expression is;

rate = k [(CH3)3CCl]

Answer:

Even all compounds are neutral.

Explanation:

Some of them exhibit polarity. Because of the difference in electron affinity of the constituent atoms, the shared electrons are pulled towards the atom with high affinity to electrons.

Answer:

63.518

Explanation:

The following data were obtained from the question:

Mass of Isotope A = 62.9 amu

Abundance of isotope A (A%) = 69.1%

Mass of isotope B = 64.9 amu

Abundance of isotope B (B%) = 30.9%

Atomic weight of the element =..?

The atomic weight of the element can be obtained as follow:

Atomic weight = [(Mass of A x A%)/100] + [(Mass of B x B%) /100]

Atomic weight = [(62.9 x 69.1)/100] + [(64.9 x 30.9)/100]

Atomic weight = 43.4639 + 20.0541

Atomic weight = 63.518

Therefore, the atomic weight of the element is 63.518.

Answer:

See the explanation

Explanation:

In this case, we have to keep in mind that in the monosubstituted product we only have to replace 1 hydrogen with another group. In this case, we are going to use the methyl group [tex]CH_3[/tex].

In the axial position, we have a more steric hindrance because we have two hydrogens near to the [tex]CH_3[/tex] group. If we have more steric hindrance the molecule would be more unstable. In the equatorial positions, we don't any interactions because the [tex]CH_3[/tex] group is pointing out. If we don't have any steric hindrance the molecule will be more stable, that's why the molecule will the equatorial position.

See figure 1

I hope it helps!

Answer:

900g of POCl₃

Explanation:

Hello,

To solve this question, we'll require the equation of reaction.

P₄O₁₀ + 6PCl₅ → 10POCl₃

Molar mass of P₄O₁₀ = 283.886 g/mol

Molar mass of PCl₅ = 208.24 g/mol

Molar mass of POCl₃ = 153.33 g/mol

But Number of moles = mass / molar mass

Mass = molar mass × number of moles

Mass of POCl₃ = 153.33 × 10 = 1533.3g

Mass of PCl₅ = 208.24 × 6 = 1249.44g

Mass of P₄O₁₀ = 283.886 × 1 = 283.886g

From the equation of reaction,

283.886g of P₄O₁₀ + 1249.44g of PCl₅ produces 1533.33g of POCl₃

I.e 1533.33g of reactants produces 1533.33g of product (law of conservation of mass)

Therefore, (225g of P₄O₁₀ + 675g of PCl₅) = 900g will give x g of POCl₃.

1533.33g of reactants = 1533.33g of products

900g of reactants = x g of products

x = (900 × 1533.33) / 1533.33

x = 900g of POCl₃

Answer: The volume of the balloon at this altitude is 46.3 L

Explanation:

Combined gas law is the combination of Boyle's law, Charles's law and Gay-Lussac's law

The combined gas equation is,

[tex]\frac{P_1V_1}{T_1}=\frac{P_2V_2}{T_2}[/tex]

where,

[tex]P_1[/tex] = initial pressure of gas = 755 mm Hg

[tex]P_2[/tex] = final pressure of gas (at STP) = 385 mm Hg

[tex]V_1[/tex] = initial volume of gas = 27.6 L

[tex]V_2[/tex] = final volume of gas = ?

[tex]T_1[/tex] = initial temperature of gas = [tex]29.9^0C=(29.9+273)K=302.9K[/tex]

[tex]T_2[/tex] = final temperature of gas = [tex]-14.1^0C=((-14.1)+273)K=258.9K[/tex]

Putting all the values we get:

[tex]\frac{755\times 27.6}{302.9}=\frac{385\times V_2}{258.9}[/tex]

[tex]V_2=46.3L[/tex]

Thus the volume of the balloon at this altitude is 46.3 L

Answer:

An ion is an atom that has lost or gained one or more electrons.

Explanation:

Ions are positively or negatively charged atoms of elements. This is because they can give, take, or share electrons with other elements to encourage the formation of chemical bonds.

Protons are what decide the chemical identity of the element. So, for example, if an atom has 11 protons, we know that will be a Sodium (Na) atom. A loss or gain of protons completely changes the chemical identity of the element and it will then become another element.

Electrons are what give an atom a neutral electrical charge (if that atom has the number of protons and neutrons normally described for the element - otherwise, a discrepancy or gain in neutrons is referred to as an isotope and declares that ions have nothing to do with the mass of an element).

With this information, you can realize that neutrons and protons have nothing to do with ions and you can confirm that ions are atoms that have lost or gained one or more electrons.

Answer:

A) How many hydrogen atoms are in the molecule?

Answer:

Option C. Keq = [SO2]² [O2] /[SO3]²

Explanation:

The equilibrium constant keq for a reaction is simply the ratio of the concentration of the products raised to their coefficient to the concentration of the reactants raised to their coefficient.

Now, let us determine the equilibrium constant for the reaction given in the question.

This is illustrated below:

2SO3(g) <==> 2SO2(g) + O2(g)

Reactant => SO3

Product => SO2, O2

Keq = concentration of products /concentration of reactants

Keq = [SO2]² [O2] /[SO3]²

Answer:

The answer is in the explanation

Explanation:

Acetic acid, CH₃COOH, is a weak acid that will produce a buffer when its conjugate base, CH₃COO⁻, acetate ion, is added to the solution.

That is because a buffer is the mixture of a weak acid and its conjugate base or vice versa.

When an acid (HX) is added to the solution, the acetate ion will react producing acetic acid, thus:

CH₃COO⁻ + HX → CH₃COOH + X⁻

For this reason, the pH doesn't change abruptly because H⁺ ions are not produced.

Now, if a  base (BOH) is added to the buffer, CH₃COOH will react producing acetate ion and water, thus:

CH₃COOH + BOH → CH₃COO⁻ + H₂O + B⁺.

In the same way, there are not produced free OH⁻ and the pH doesn't change significantly.

Answer:

Ba(+2)(aq) + SO4(-2)(aq) -----> BaSO4(s)

Explanation:

Take a look at the attachment below;

Answer:

997.65cmH2O

Explanation:

Barometric pressure = 739 mmHg

density of Hg = 13.5 g/ml

density of water (H2O) = 1.00 g/ml

Calculate Barometric pressure in centimetres of water ( cmH20)

equate the barometric pressure of Hg and water

739 * 13.5 * 9.8 = x * 1 * 9.81

x ( barometric pressure of water in mmH2O ) = 739 *13.5 / 1 = 9976.5mmH2O

in cmH2O = 997.65cmH2O

Answer:

The lock-and-key model:

c. Enzyme active site has a rigid structure complementary

The induced-fit model:

a. Enzyme conformation changes when it binds the substrate so the active site fits the substrate.

Common to both The lock-and-key model and The induced-fit model:

b. Substrate binds to the enzyme at the active site, forming an enzyme-substrate complex.

d. Substrate binds to the enzyme through non-covalent interactions

Explanation:

Generally, the catalytic power of enzymes are due to transient covalent bonds formed between an enzyme's catalytic functional group and a substrate as well as non-covalent interactions between substrate and enzyme which lowers the activation energy of the reaction. This applies to both the lock-and-key model as well as induced-fit mode of enzyme catalysis.

The lock and key model of enzyme catalysis and specificity proposes that enzymes are structurally complementary to their substrates such that they fit like a lock and key. This complementary nature of the enzyme and its substrates ensures that only a substrate that is complementary to the enzyme's active site can bind to it for catalysis to proceed. this is known as the specificity of an enzyme to a particular substrate.

The induced-fit mode proposes that binding of substrate to the active site of an enzyme induces conformational changes in the enzyme which better positions various functional groups on the enzyme into the proper position to catalyse the reaction.

Answer:

See explanation

Explanation:

In this case, we have 2 types of reactions. [tex]CH_3CH_2ONa[/tex] is a strong base but only has 2 carbons therefore we will have less steric hindrance in this base. So,  the base can remove hydrogens that are bonded on carbons 1 or 6, therefore, we will have a more substituted alkene (1-methylcyclohex-1-ene).

For the  [tex]KOC(CH_3)_3[/tex] we have more steric hindrance. So, we can remove only the hydrogens from carbon 7 and we will produce a less substituted alkene (methylenecyclohexane).

See figure 1

I hope it helps!

Answer:

8

Explanation:

When you balance the entire equation, you should get:

C5H12 + 8O2 ---> 5CO2 + 6H2O

Answer:

B. None of these

Explanation:

Sulfur has less ionization energy than phosphorus because sulfur has a pair of electron in its 3p subshell that increases electron repulsion in sulfur and sulfur electrons can easily remove from its sub-level.

While, there are no electron pairs in 3p subshell of phosphorus, therefore it requires more energy to remove an electron from 3p subshell.

Hence, the reason is electron repulsion and the correct answer is B.

Answer:

315mL

Explanation:

Data obtained from the question include the following:

Molarity of stock solution (M1) = 0.135 M

Volume of stock solution needed (V1) =?

Molarity of diluted solution (M2) = 0.0851 M

Volume of diluted solution (V2) = 500mL

The volume of the stock solution needed can be obtain as follow:

M1V1 = M2V2

0.135 x V1 = 0.0851 x 500

Divide both side by 0.135

V1 = (0.0851 x 500) / 0.135

V1 = 315mL

Therefore, the volume of the stock solution needed is 315mL

Answer:

H = 4,034,250 J

Explanation:

Mass, m = 165kg = 165,000g (Converting to grams)

Initial temperature = 15.7°C

Final temperature = 95.7°C

Temperature change, ΔT = 95.7 - 15.7 = 50°C

Specific heat capacity, c = 0.489 J/g·°C

Heat = ?

All the parameters are related with the equation below;

H = m * c * ΔT

H = 165000 * 0.489  * 50

H = 4,034,250 J

Answer: 9.53 *2= 19.06

Explanation:

The law of multiple proportions states that if two elements combines to form more than one compound the ratio of masses of the second element which combines to the fixed mass of the first element will always be the ratios of the small whole numbers.

in case of carbon monoxide, mass of carbon will be the same of mass of oxygen.

But in case of carbon dioxide, if carbon is 9.53 units then oxygen will be twice as that of carbon.

CO2, so 9.53*2= 19.06 grams of oxygen will combine with 9.53 grams of carbon to form carbon dioxide.