The half-life of radium-226 is 1590 years. (a) A sample of radium-226 has a mass of 50 mg. Find a formula for the mass of the sample that remains after t years. (b) Find the mass after 500 years correct to the nearest milligram. (c) When will the mass be reduced to 40 mg

Answer:

1. Acid-Base Reaction

Explanation:

Fe(OH)2(s) + HCl(aq) = FeCl2(aq) + H2O(l)

base               acid

This a reaction between base and acid.

Ferrous hydroxide is an inorganic alkaline compound whereas hydrochloric acid is an acid. The reaction between Fe(OH)₂and HCl is an acid-base reaction. Thus, option 1 is correct.

An acid-base reaction is a chemical change that occurs and takes place when the reactant constitutes an acid and a base. They are characterized by the exchange of protons that results in the formation of conjugate bases and acids or salt.

The acid-base chemical reaction is shown as,

Fe(OH)₂(s) + HCl(aq) ⇒ FeCl₂(aq) + H₂O(l)

Here, ferrous hydroxide is a base with hydroxide ions and hydrochloric acid is an acid with hydrogen ions. HCl donates its proton to form water molecules with hydroxide ions of ferrous hydroxide.

Therefore, in option 1. the reaction is an acid-base reaction.

Learn more about acid-base reaction, here:

https://brainly.com/question/14276012

#SPJ2

Explanation:

Benzene is colorless, with a sweet odour.

Color of Bromine is reddish brown .

Hope this helps.

Answer:

7.25 x 10^47

Explanation:

1.204 x 10^24 moles*6.022 x 10^23 avogadro's number= 7.25 x 10^47

Answer:

30 mL VOLUME OF 3.0 M HCl SHOULD BE USED BY THE STUDENT TO MAKE A 1.80 M IN 50 mL OF HCl.

Explanation:

M1 = 3.00 M

M2 = 1.80 M

V2 = 50 .0 mL = 50 /1000 L = 0.05 L

V1 = unknown

In solving this question, we know that number of moles of a solution is equal to the molar concentration multiplied by the volume. To compare two samples, we equate both number of moles and substitute for the required component.

So we use the equation:

                                  M1 V1 = M2 V2

V1 = M2 V2 / M1

V2 = 1.80 * 0.05 / 3.0

V2 = 0.09 /3.0

V2 = 0.03 L or 30 mL

To prepare the sample of 1.80 M HCl in 50.0 mL from a 3.0 M HCl, 30 mL volume should be used.

Answer:

Explanation:

i dont like reading

Answer:

vaporization

Explanation:

The molar enthapy of _vaporization______ is the heat required to vaporize one mole of a liquid”

Answer:

1. Non-target

2. Bycatch

Explanation:

In the fishing industry, the main aim of the industry is to capture fishes that can be used or eaten and sell. A variety of fishes are captured for this purpose and since they are used therefore are known as Target catch.

But there are some species which has to be discarded because they are toxic and not useful. These non-useful species like eel which gets captured in the net while capturing other fishes are known as Non-target fish.

The eel fish which gets captured is known as bycatch fishes in the fishing operation.

Thus, Non-target and Bycatch are the correct answer.

Answer:

Its just bycatch

Explanation:

The eel species is called a(n) bycatch of the fishing operation.

Answer:

THE INITIAL TEMPERATURE OF THE SECOND SAMPLE IS 4.93 C OR 277.93 K

Explanation:

Mass of first sample of water = 106 g

Initial temp of first sample = 21.4  °C = 21.4 + 273 K = 294.4 K

Mass of second sample = 64.3 g

Final temp of theresulting mixture = 46.8  °C = 46.8 + 273 K = 319.8 K

Specific heat capacity of water = 4.184 J/g K

It is worthy to note that;

Heat gained by the first sample = Heat lost by the second sample

Since heat = mass * specific heat capacity * change in temperature, we have

Mass * specific heat * change in temp of the first sample  = Mass * specific heat * change in temp. of the second sample

MC (T2 - T1) = MC (T2-T1)

106 * 4.184 * ( 319.8 - 294.4) = 64.3 * 4.184 * ( 319.8 - T1)

106 * 4.184 * 25.4 = 269.0312 ( 319.8 - T1)

11 265.0016 = 269.0312 (319.8 - T1)

Since the change in temperature = 319.8 -T1

Change in temperature =11265.0016 / 269.0312

Change in temperature =  41.87

Change in temperature = 319.8 -T1

41.87 = 319.8 - T1

T1 = 319.8 - 41.87

T1 = 277.93 K

T1 = 4.93  °C

So therefore, the initial temperature of the sacond sample is 4.73  °C or 277.93 K

You need to know the amount of heat generated by the combustion reaction.

Assuming propane as fuel, you can use thiis data:

C3H8(g)+5O2(g)---3CO2(g)+4H2O(g) ΔH= -2217 KJ

So when 3 moles of CO2 is emmitted 2217 kJ of heat is produced.

The molar wegiht of CO2 is 12 g/mol + 2 * 16 g/mol = 44 g/mol.

Then 3 mol * 44 g / mol = 132 g of CO2 are produced with 2217 kJ of heat.

Now you have to calculate how much energy you need to produce if only 12% is abosrbed by the pork

Energy absorbed by the pork = 12% *  total energy =>

total energy = energy absorbed by the pork / 0.12 = 1700 kJ / 0.12 = 14,166.67 kJ.

Now, state the proportion:

132 g CO2 / 2217 kJ = x / 14,166.7 kJ =>

x = 14,166.67 * 132 / 2217 = 843.48 g CO2.

Answer: 843 g of CO2

Answer:

b. the heating of 10 g of liquid water from 0°C to 100°C.

Explanation:

Hello,

In this case, we must notice a., c. and d. processes are not actually absorbing heat but releasing it since cooling, freezing and condensation are processes with negative heat sign since matter changes from a state of more energy to a state of less energy. We can prove this by realizing that freezing enthalpy of water is -6.00 kJ/mol, condensation enthalpy of eater is -40.8 kJ/mol and a change of temperature from 100 °C to 0 °C is negative.

In such a way, the only process absorbing heat is b. the heating of 10 g of liquid water from 0°C to 100°C since energy must be added to the system, or absorbed by it in order to attain the heating.

Regards.

The process having the greatest amount of heat is:

b. the heating of 10 g of liquid water from 0°C to 100°C.

The options a., c. and d. processes are not actually absorbing heat but releasing it since cooling, freezing and condensation are processes with negative heat sign since matter changes from a state of more energy to a state of less energy.

The freezing enthalpy of water is -6.00 kJ/mol, condensation enthalpy of eater is -40.8 kJ/mol and a change of temperature from 100 °C to 0 °C is negative.

So out of all the options, only process at b is a heating process thus it will absorb greatest amount of heat.

Find more information about Heat here:

brainly.com/question/13439286

Answer:

[Ne] 3s² 3p⁴

Electrons per shell: 2,8,6

Answer : 2,8,6 (Sulphur Atom)

                2,8,8 (Sulphur Ion)

Answer:

Osmium

Explanation:

If you take a look at the attached image of a periodic table below, you will see that the element in the 6th period and 8th group is Osmium. Hope this helps!

Answer:

D. Nitrogen has 5 valence electrons.

Explanation:

Nitrogen is an element in group 5A of the periodic table. Elements in group 5A all contain just 5 valence electrons. (Electrons in the outer shell).

**Elements are organized into these groups in a periodic table based on the number of valence electrons which determines their charge. (Does not apply to transition metals)

Answer: Thus the mass, in grams, of 27 moles of smooth muscle myosin is 12960000 grams

Explanation:

According to avogadro's law, 1 mole of every substance weighs equal to the molecular mass, occupies 22.4 L at STP  contains avogadro's number [tex](6.023\times 10^{23})[/tex] of particles.

Molecular mass of protein = 480,000 g/mol

Thus 1 mole of protein weighs = 480,000 g

So 27 moles of protein weighs = [tex]\frac{480,000}{1}\times 27=12960000g[/tex]

Thus the mass, in grams, of 27 moles of smooth muscle myosin is 12960000 grams

Answer:

pH = 8.75

Explanation:

100.0mL of a 0.8108M of a butanoic acid (HC₃H₇CO₂, pKa 4.82) solution is titrated with 0.0520M KOH.

The reaction is:

HC₃H₇CO₂ + KOH → H₂O + KC₃H₇CO

Moles of butanoic acid are:

0.1000L × (0.8108mol / L) = 0.08108 moles of butanoic

For a complete reaction, volume of KOH must be added is the volume in which 0.08108 moles of KOH are added, that is:

0.08108 mol × (L / 0.0520mol) = 1.56L of KOH.

Total volume in equilibrium is 1.56L + 0.10L = 1.66L

That means concentration of butanoic acid is:

0.08108 mol / 1.66L = 0.04884M HC₃H₇CO₂

At equivalence point, there is just C₃H₇CO⁻ in solution

Kb of butanoic acid is:

C₃H₇CO⁻ + H₂O ⇄ HC₃H₇CO₂ + OH⁻

Kb = Kw / Ka

Ka = 10^-pKa

Ka = 1.51x10⁻⁵

Kb = 1x10⁻¹⁴ / 1.51x10⁻⁵ = 6.61x10⁻¹⁰

The equilibrium of Kb is:

Kb = 6.61x10⁻¹⁰ =  [HC₃H₇CO₂] [OH⁻] / [C₃H₇CO⁻]

As at equivalence point there is just C₃H₇CO⁻, the equilibrium concentrations are:

[C₃H₇CO⁻] = 0.04884M - X

[HC₃H₇CO₂] = X

[OH⁻] = X

Replacing in Kb:

6.61x10⁻¹⁰ =  X² / [0.04884M - X]

0 =  X² + 6.61x10⁻¹⁰X - 3.23x10⁻¹¹

Solving for X:

X = -5.68x10⁻⁶ → False solution. There is no negative concentrations

X = 5.683x10⁻⁶ → Right solution.

As [OH⁻] = X, [OH⁻] = 5.683x10⁻⁶.

pOH = - log [OH⁻]

pOH = 5.245

pH = 14 - pOH

Answer:

3–bromo–5–chloro–4–methylhexane.

Explanation:

To name the compound given in the question, the following must be observed:

1. Locate the longest continuous carbon chain. This gives the parent name of the compound. In this case, the longest chain is carbon 6 i.e Hexane.

2. Identify the substituents attached. In this case the substituents attached are:

a. Chloro i.e Cl.

b. Bromo ie Br.

c. Methyl i.e CH3.

3. Give the substituents the lowest possible count alphabetically. Bromo comes before Chloro alphabetically, so we shall consider bromo first. Their positions are given below:

Bromo i.e Br at carbon 3

Chloro i.e Cl is at carbon 5

Methyl i.e CH3 is at carbon 4

4. Combine the above to get the name of the compound.

Therefore, the name of the compound is:

3–bromo–5–chloro–4–methylhexane.

Answer:

FOR EVERY 10 DEGREE CELSIUS INCREASE IN TEMPERATURE, THE ACTIVATION ENERGY THAT SHOWS THIS IS 52.4 KJ/MOL

Explanation:

From Arrhenius equation, the relationship between the rate constant and the temperature is as shown below:

k = Ae^ -Ea/RT

At initial temperature T1, the initial rate constant is (k1)

At final temperature T2, the final rate constant is k2

For the reaction rate to be doubled, we must double the rate constant which shows that the ratio of k2 / k1 must be equal to 2.

That is, k2 / k1 = 2 (rate is doubled)

Equating this into the Arrhenius equation, we have:

k2 / k1 = Ae^ (-Ea / R ) (1/ T2 - 1/T1)

2 = e^ (-Ea / R) (1 / T2 = 1 / T1)

Taking the natural logarithm of both sides:

ln 2 = - (Ea / R) (1 / T2 - 1 / T1)

Making Ea the subject of the formula, we obtain:

Ea = - (ln 2 R / (1 / T2- 1 / T1))

Let T1 = 25 C = 25 + 273 K = 298 K

T2 = 35 C = 35 + 273 K = 308 K

R = 8.314

So,

Ea = - (ln 2 * 8.314 / ( 1/308 - 1 / 298))

Ea = - (0.693 * 8.314 / 0.00324 - 0.00335)

Ea = - 5.7616 / -0.00011

Ea = 52 378,18 J / mol

So therefore, the activation energy Ea is 52.4 kJ/mol.

Answer:

The balanced equation is given below:

SiO2 + 4HF —> SiF4 + 2H2O

The coefficients are 1, 4, 1, 2

Explanation:

The equation for the reaction is given below:

SiO2 + HF —> SiF4 + H2O

The above equation can be balance by as follow:

There are 4 atoms of F on the right side and 1 atom on the left side. It can be balance by putting 4 in front of HF as shown below:

SiO2 + 4HF —> SiF4 + H2O

Therefore are 4 atoms of H on the left side and 2 atoms on the right side. It can be balance by putting 2 in front of H2O as shown below:

SiO2 + 4HF —> SiF4 + 2H2O

Now the equation is balanced.

Answer:

Hypothesis is an assumption or idea about a particular topic or argument. An hypothesis should be one which is able to be tested and measurable to determine its authenticity.

A theory is an explanation of a scientific observation which has undergone series of experiments and is reproducible in any part of the world.

A law is simply a rule which gives an in depth explanation of a scientific finding. If new findings emerge the law could be changed or modified.

Answer:

7 mol

Explanation:

Caffeine molecular formula C8H10N4O2. It has 2 atoms of oxygen.

                          C8H10N4O2         - 2O

                           1 mol                        2 mol

                           3.5 mol                    x mol

x = 3.5*2/1 = 7 mol

Answer:

The weakest conjugate is HClO-.

Explanation:

As a general rule, the stronger the Bronsted-Lowry acid, the weaker its conjugate base, and vice versa.  

Acid 1: HClO is a strong acid, hence its conjugate base would be weak

Acid 2: H3PO4 is a weak acid, hence its conjugate base would be strong

Acid 3: hydrogen sulphide is also a moderately weak acid with a moderately strong conjugate base.

In order of increasing strengths:

HClO < H2S < H3PO4

Answer:

1. In order to reach equilibrium COCl₂(g) must be consumed.

B. False

2. In order to reach equilibrium Kc must increase.

B. False .

3. In order to reach equilibrium CO must be consumed.

A. True.

4. Qc is greater than Kc.

A. True

5. The reaction is at equilibrium. No further reaction will occur.

B. False.

Explanation:

Based on the reaction:

COCl₂(g) → CO (g) + Cl₂(g)

And Kc is defined as:

Kc = 1.29x10⁻² = [CO] [Cl₂] / [COCl₂]

Molar concentrations of each species are:

[COCl₂] = 0.104 moles of COCl₂ / 1L = 0.104M

[CO] = 4.66×10⁻² moles of CO / 1L = 4.66×10⁻²M

[Cl₂] = 3.76×10⁻² moles of Cl₂ / 1L = 3.76×10⁻²M

Replacing in Kc formula:

4.66×10⁻²M × 3.76×10⁻²M / 0.104M = 1.68x10⁻²

As the concentrations are not in equilibrium, 1.68x10⁻² is defined as the reaction quotient, Qc.

As Qc > Kc, the reaction will shift to the left producing more COCl₂ and consuming CO and Cl₂. Thus

1. In order to reach equilibrium COCl₂(g) must be consumed.

B. False

2. In order to reach equilibrium Kc must increase.

B. False . Kc is a constant that never change.

3. In order to reach equilibrium CO must be consumed.

A. True.

4. Qc is greater than Kc.

A. True

5. The reaction is at equilibrium. No further reaction will occur.

B. False. The reaction is in equilibrium when Qc = Kc

Answer:

Hydrogen peroxide is ans

Answer:

A

Explanation:

Arsenic is in the same group as Nitrogen - group 5. They all have 5 valence electrons in their outermost shell. To achieve its most stable state - 8 valence electrons (octet rule - elements are most stable when the entire shell is filled) - arsenic needs to gain 3 electrons. Since electrons have a negative charge, the charge of an As ion would be -3.

Try observing the periodic table and how many valence electrons that each element has. From there, you can determine the charges of the elements lithium and strontium. You can guess, I'll help you with those once you attempt to find the charge of those ions.

Answer:

Sol is a colloidal suspension with solid particles in a liquid. Foam is formed when many gas particles are trapped in a liquid or solid. Aerosol contains small particles of liquid or solid dispersed in a gas. While solid solution contain solid as solute in either solid, liquid or gas.

Explanation:

We know that more is the [tex]pK_{a}[/tex] value, weaker will be the acid. Also, an acid completely dissociates into ions in an aqueous base solution when [tex]pK_{a}[/tex] of conjugate acid of base is greater than acid.

4-methylphenol [tex](CH_{3}C_{6}H_{4}OH)[/tex] ([tex]pK_{a} = 10.26[/tex]) is quite soluble in its sodium salt. In NaOH, the dissociation will be as [tex]Na^{+}[/tex] and [tex]OH^{-}[/tex] ions as NaOH is a strong base.

Therefore, 4-methylphenol will readily dissolve in NaOH solution.

As, [tex]NaHCO_{3}[/tex] is not a strong base but as 4-Methylphenol forms a sodium salt hence, it will have a low solubility as compared to NaOH.

Whereas [tex]Na_{2}CO_{3}[/tex] is not a base but when dissolved in water it shows basic character as it produces NaOH (strong base) and [tex]H_{2}CO_{3}[/tex] (weak acid). As a result, the solution gets basic. Hence, 4-methylphenol will readily dissolve in [tex]Na_{2}CO_{3}[/tex].

Answer: they blow up

Explanation: add them together and they will blow up

Answer:

Magnesium nitrate Reactions

Magnesium nitrate has a high affinity towards water. Therefore, heating it results to decompose into magnesium oxide, nitrogen oxides, and oxygen. 2 Mg(NO3)2 → 2 MgO + 4 NO2 + O2.

Answer:

1.73 M

Explanation:

We must first obtain the concentration of the concentrated acid from the formula;

Co= 10pd/M

Where

Co= concentration of concentrated acid = (the unknown)

p= percentage concentration of concentrated acid= 37.3%

d= density of concentrated acid = 1.19 g/ml

M= Molar mass of the anhydrous acid

Molar mass of anhydrous HCl= 1 +35.5= 36.5 gmol-1

Substituting values;

Co= 10 × 37.3 × 1.19/36.5

Co= 443.87/36.6

Co= 12.16 M

We can now use the dilution formula

CoVo= CdVd

Where;

Co= concentration of concentrated acid= 12.16 M

Vo= volume of concentrated acid = 35.5 ml

Cd= concentration of dilute acid =(the unknown)

Vd= volume of dilute acid = 250ml

Substituting values and making Cd the subject of the formula;

Cd= CoVo/Vd

Cd= 12.16 × 35.5/250

Cd= 1.73 M

Answer:

they must be heated

Explanation: