I need these 3 questions answered with work shown :( I’m so bad at chem

Answer:Adding or removing energy from matter causes a physical change as matter moves from one state to another. For example, adding thermal energy (heat) to liquid water causes it to become steam or vapor (a gas). And removing energy from liquid water causes it to become ice (a solid)

Explanation:

Answer:  -1.67 KJ

Explanation:

Given- m of water= 21g

           Final temperature- 67°C

           Initial temperature- 86°C

           Specific heat capacity of water ( c)= 4.182 J/g°C

Solution

Q= mcΔT

Q= 21g* 4.182J/g°C*(67°C-86°C) = -1669J

For calculations involving data having 2 significant figures, the value that will be used for the number of joules in a calorie is 1 cal = 4.2 J.

Rounding off implies simplifying a number by preserving its value but moving it closer to the next number. It is done for whole numbers as well as decimals at various places of hundreds, tens, tenths, and so on. Numbers are rounded off to maintain important digits. The number of important figures in a result is simply the number of figures that are reliably known.

Estimation is a sort of rounding-off. Estimation is employed in daily life as well as in areas such as mathematics and physics. Many physical values, such as money, distance traveled, length measured, and so on, are approximated by rounding off the actual number to the next whole number.

If the digit in the smallest spot is less than 5, it is left alone. Rounding down occurs when any number of digits following that number reaches zero.

If the digit in the smallest position is larger than or equal to 5, it is multiplied by +1. Rounding up occurs when any digits following that number reach zero.

Therefore, by rounding off, 1 cal = 4.2 J.

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Answer:

isotopes of elements with unstable nucleus releases nuclear radiation. generally the instability is related to the neutron to proton ratio in the nucleus of an atom

There are 27 atoms in total in Cr₂(S₂O₃)5.

Atoms are the smallest possible amount of matter which still retains its identity as a chemical element and now known to consist of a nucleus surrounded by electrons.

Atoms are contained in elements. This means there are atoms in hydrogen, oxygen, chlorine etc.

According to this question, a compound with the chemical formula Cr₂(S₂O₃)5 is given. The number of atoms in this compound can be calculated as follows:

In this compound, there are;

This means that in total, 27 atoms are present in Cr₂(S₂O₃)5.

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Answer:

4.85 grams HBr

Explanation:

To find the mass of hydrogen bromide (HBr), you need to multiply the given moles by the molar mass. The molar mass of HBr is a ratio which compares the mass (g) of HBr per every 1 mole. It is important to arrange the ratio in a way that allows for the cancellation of units (moles should be in the denominator).

Molar Mass (HBr): 1.008 g/mol + 79.904 g/mol

Molar Mass (HBr): 80.912 g/mol

0.0600 moles HBr            80.912 g
------------------------------  x  --------------------  =  4.85 grams HBr
                                             1 mole

Answer:

The reaction of citric acid and sodium bicarbonate is written as H_3C_6H_5O_7(aq) + 3 NaHCO_3(aq)

Explanation:

Karen drove 0.3 hours to the east at constant velocity for 30 km. The velocity of Karen when she drove towards east is 100 km/ h.

Velocity is defined as a direction of movement of the body or the object.

It is a vector quantity. It is the rate of change of distance and rate of change of displacement.

It is a fundamental concept in kinematic, the branch of classical mechanics that describes the motion of body.

Velocity can be expressed as

Velocity = distance / time

              = 30km / 0.3 h

              = 100 km/h

Thus, the velocity of Karen when she drove towards east is 100 km/ h.

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The ion is the indium ion. There are no unpaired electrons in the ground state of this ion.

Electronic configuration can be described as the arrangement of electrons in orbitals around an atomic nucleus.

The electron configuration of atoms shows the arrangement of the electrons of the atom in specific atomic orbitals. The electron configuration of the atom can be used to identify the atom or the ion.

Indium forms the ion with a charge of +1 after the removal of one electron from the 5p orbital. This results in an electron configuration of  [Kr]4d105s2 where all subshells are fully filled.

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The second circle has the greatest number of species diversity .

The term genetic diversity has to do with the existence of different species in a habitat. We know that due to natural selection, only the organisms that have traits that enable them to survive longer and reproduce are better adapted in the ecosystem. Thus, other species may begin to dwindle and even disappear in the ecosystem.

Genetic diversity ensures that there are different species in the habitat. In each circle, we see that the colors represent the different species of the organisms in the habitat. The habitat with the most number of different colors is the habitat that has the greatest magnitude of species diversity.

Hence, the second circle has the greatest number of species diversity as indicated in the image attached to this answer.

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Diamond yields the largest mass of carbon monoxide.

The term combustion has to do with the burning of a substance in oxygen. Now we know that when we burn a substance in oxygen, the substance is oxidized.

The burning of a hydrocarbon in air gives carbon dioxide and water. We could sometimes obtain a low concentration of carbon monoxide when the combustion is carried out in a poor supply of air.

However, when we burn diamond in air which largely consists of carbon, we can see that the product of the reaction is carbon monoxide.

Thus diamond yields the largest mass of carbon monoxide.

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Mass (in g) of the excess reactant is left is 28.39 g and mass is measure of the amount of matter that an object contains

Mass of reactants is equal to the mass of products if the reaction has the same number of atoms of different elements on either side of the chemical equation respectively.

Here molar mass of P₄ = 31.0×4g/mol = 124.0g/mol

Molar mass of Cl₂ = 35.5×2g/mol = 71.0g/mol

Molar mass of PCl₃ = 31.0+35.5×3g/mol = 137.5g/mol

Initial no of moles of P₄ = 45.13g/124.0g/mol = 0.3639 mol

Initial no of moles of Cl₂ = 132.0g/71.0g/mol = 1.859 mol

Balanced equation for reaction,

P₄+6Cl₂→4PCl₃

Mole ratio P₄ : Cl₂ : PCl₃ = 1 : 6 : 4

If Cl₂ completely react P₄ needed  = 1.859 ×1/6 = 0.3098<0.3639mol

Hence, P₄ is in excess and Cl₂ is the limiting reactant

No of moles of  PCl₃ produced = 0.3098mol×4/6 = 0.2065mol

Mass of PCl₃ produced = 0.2065×137.5g/mol

= 28.39g

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The amount of work involved in a chemical reaction is 236.9 J.

The energy required to move a system or body or anything against a force or external pressure is called work.

The amount of work involved in a chemical reaction if the volume decreases from 4.00 to 1.34 L against a constant pressure of 0.879 atm  is calculated as follows;

W = PΔV

where;

W = 0.879atm (4L - 1.34L)

W = 2.338 atm.L

1 atm.L = 101.325 J

2.338 atm.L = ?

= 236.9 J

Thus, the amount of work involved in a chemical reaction is 236.9 J.

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The frequency (in reciprocal seconds) of electromagnetic radiation with a wavelength of 1.15 cm is 0.005x[tex]10^{-8}[/tex]Hz.

The frequency of a repeated event is its number of the instances per unit of time. In some cases, it is also referred to as the temporal frequency or ordinary frequency to underline the differences with spatial and angular frequencies, respectively. One (event) per second is equal to the one hertz (Hz), which is how frequency is stated. The period is the reciprocal of frequency since it is the length of time for one cycle in a repeating occurrence.

The temporal rate of change observed in oscillatory and periodic phenomena, such as mechanical vibrations, audio signals (sound), radio waves, and light, is specified by frequency, an essential parameter in science and engineering.

The main formula is

L = V / F so F= V/L

L= wavelength = 1.15 cm=0.015m

V= speed of the light=3 x [tex]10^{8}[/tex] m/s

finally,

F= 0.015/3x10^8=0.005 x[tex]10^{-8}[/tex] Hz

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The statement describes the advantage of this model of the solar system is  that The students can infer information about the effects of gravity on each planet. Option D

The solar system is composed of the sun and the planets. It has to do with a set up in which the sun lies at the center. We call this the heliocentric model of the solar system.

Given that we have taken the school to be the sun which lies at the center of the solar system and the position of the planets have been scaled using 1 AU = 100 meters (the length of a football field).

The only thing that is given in the options that we can not infer from this set up is the fact that; the students can infer information about the effects of gravity on each planet.

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If 2 moles of AlCl₃ reacts as shown in the balanced equation, 3 moles of MgCl₂ will be produced.

Stoichiometry is the study and calculation of quantitative (measurable) relationships of the reactants and products in chemical reactions (chemical equations).

According to this question, aluminum chloride reacts with magnesium phosphate to produce aluminum phosphate and magnesium chloride as follows:

2AlCl3 + Mg₃P₂ → 2AlP + 3MgCl₂

Based on the above balanced reaction, 2 moles of aluminum chloride (AlCl₃) formed 3 moles of magnesium chloride (MgCl₂).

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The mass of the liquid gold is 25 grams because the same number of atoms will be present in the liquid and the solid.

The smallest component of ordinary matter that makes up a chemical element is an atom. Atoms that are neutral or ionised make up every solid, liquid, gas, and form of plasma. Atoms are incredibly tiny, usually measuring 100 picometers across.

The smallest piece of matter that can be divided without sending electrically charged particles flying. It is also the smallest piece of matter with chemical element-like characteristics. As a result, the atom serves as the fundamental unit of chemistry.

According to the given value;

The density will decrease from 19.30 g/cm3 (solid gold room temp) to 17.31 g/cm3 (at melting point). And volume will increase because the atoms will be loosely connected.

The mass of the liquid gold is 25 grams because the same number of atoms will be present in the liquid and the solid.

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The alkali metals hydrogen (H), lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (F) are found in Group 1A of the periodic table (Fr).

Because of the orderly arrangement of the elements, it is known as the periodic table. They're arranged in rows and columns, as you'll see. The vertical columns that go from top to bottom and the horizontal rows that travel from left to right are referred to as Periods and Groups, respectively.

All known elements are grouped together in the periodic table of elements into groups with related properties. As a result, it becomes a vital tool for chemists, nanotechnologists, and other researchers. If you can utilize and understand the periodic table, you can predict how compounds will react.

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Answer:

Gold is an element

Explanation:

Elements are only 1 atom

Mixtures can be multiple atoms or compounds, but not chemically bonded

Compounds are atoms chemically bonded together

Nuclear reactions such as that of uranium alpha particle involves a change in an atom's nucleus and produces a different element.

Non-nuclear reactions such as reaction of sodium with chlorine on the other hand, involve only a rearrangement of electrons and do not involve changes in the nuclei.

A nuclear reaction is a process in which two nuclei, or a nucleus and an external subatomic particle, collide to produce one or more new nuclides.

There are some differences between a nuclear reaction and a non nuclear reaction.

Nuclear reactions involve a change in an atom's nucleus, usually producing a different element. Non nuclear reactions, on the opposite end involve only a rearrangement of electrons and do not involve changes in the nuclei.

In conclusion, nuclear reaction are processes in which one or more nuclides are produced from a collision between two nuclei or one nucleus and a subatomic particle.

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Answer:

0.0939 moles Cu

Explanation:

To find the amount of copper in moles, you need to multiply the given mass (g) by the atomic mass (g/mol) of copper. The atomic mass is a ratio which represents the mass of copper per every 1 mole. The ratio should be arranged in a way that allows for the cancellation of units (grams should be in the denominator to cancel the units of the starting mass). The final answer should have 3 sig figs like the given value (5.97 g = 3 sig figs).

Atomic Mass (Cu): 63.546 g/mol

 5.97 g Cu            1 mole
------------------  x  ------------------  =  0.0939 moles Cu
                            63.546 g

alin sa sumusunod ang nagpapahayag ng tunay na pagmamahal batay sa mitong psyche at cupid

The solubility of the given solutes in the solvents are as follows:

The solubility of a substance in a solvent is the amount of that substance that dissolves in a given volume of the solvent.

The substance that is dissolved in a solvent is known as the solute.

The solubility of  a solute in a solvent depends on both the nature of the solute as well as the solvent.

For example, polar substances dissolve in polar solutes but not i non-polar solvents, whereas, non-polar solutes dissolves in non-polar solvents but not in polar solvents. This is known as the principle of like dissolves like.

Considering the given solutes and the solvents to determine the solubility of the solutes in the given solvents:

Water:

Salt and Sugar dissolves in water but Flour does not dissolve in water.

Hydrogen peroxide:

Salt and Sugar dissolves in hydrogen peroxide but Flour does not dissolve in hydrogen peroxide.

Isopropyl alcohol:

Sugar dissolves in isopropyl alcohol but Salt and Flour does not dissolve in isopropyl alcohol.

Mineral oil:

Flour dissolves in mineral oil but Salt and Sugar does not dissolve in mineral oil.

Vinegar:

Sugar dissolves in vinegar but Salt and  Flour does not dissolve in vinegar.

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1) The Molarity of first solution is 0.163 M

2) The molarity of second solution is 0.344 M

1) Molarity is defined as the no. of moles of solute per liter solution.

First solution contains 0.450 mol of NaOH in 2.75 L of solution.

M = n / V

where , n= no, of moles of solute

V  = volume of solution in liter

no. of moles of solute = 0.450 mol

M =  0.450 / 2.75 = 0.163 M

Molarity = 0.163 M

2) Th second solution contains 15.1 g of NaCl in 749 ml of solution.

moles = mass / molar mass

          =  15.1 g / 58.44 g/mol

          =  0.258 mols

volume = 749 ml = 0.749 L

M =  0.258 / 0.749

    = 0.344 M

Molarity = 0.344M

Thus, 1) The Molarity of first solution is 0.163 M

2) The molarity of second solution is 0.344 M

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A sample of the male sex hormone testosterone C₁₉H₂₈O₂, contains 3.58 × 10²¹ atoms of hydrogen. It contain 2.42 × 10²¹ carbon atoms.

To find the number of moles use this formula

Number of moles = Number of atoms / Avogadro's Number

Here,

Number of atoms = 3.58 × 10²¹

Avogadro's Number = 6.022 × 10²³

Now, put the values in above formula we get

Number of moles = Number of atoms / Avogadro's Number

                             =  3.58 × 10²¹ / 6.022 × 10²³

                             = 5.94 × 10⁻³

1 mol testosterone C₁₉H₂₈O₂ contains 28 mole of hydrogen atoms

Now, 5.94 × 10⁻³ moles contains = (1/28) × 5.94 × 10⁻³

                                                      = 2.12 × 10⁻⁴ mol

To find the number of atoms use this formula

Number of atoms = Number of moles × Avogadro's Number

Here,

1 mol testosterone C₁₉H₂₈O₂ contains 19 mole of carbon atoms

Number of moles = 19 moles

Avogadro's Number = 6.022 × 10²³

Now put the value in above formula we get

Number of atoms = Number of moles × Avogadro's Number

                              = 19 ×  6.022 × 10²³

                              = 1.14 × 10²⁵

Now the no. of C-atoms =  1.14 × 10²⁵ × 2.12 × 10⁻⁴ mol

                                        = 2.42 × 10²¹ carbon atoms.

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Note: The given question is incomplete on the portal here is the complete question.

Question: A sample of the male sex hormone testosterone C₁₉H₂₈O₂, contains 3.58 × 10²¹ atoms of hydrogen. How many carbon atoms does it contain ?

1.769 grams of Rn-226 still exist after three half-lives.

Half-life of a substance is the time required by the substance to reduce to half of the initial value.It is used to explain how fast unstable atoms undergo radioactive decay.It is a constant for a lifetime of an exponentially decaying substance.

Formula of half-life when number of days and radioactive decay are given respectively as,

N[tex]_(t)[/tex]=N₀(1/2)[tex]_t[/tex]

λ=0.693/t[tex]_1/2[/tex]

According to the question given data is,

initial amount (N₀)=6.0 g

half life (t[tex]_1/2[/tex])=3.8 days

To calculate final mass after 3 half lives,days in 3 half-lives are calculated as,number of half lives×each half life period=3×3.8=11.4 days

Number of atoms existing after 11.4 days =N₀(1/2)[tex]^11.55[/tex]=N₀/3.391=6/3.391=1.769 g

Therefore,1.769 g of Rn-226 still exist after three half-lives.

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The strongest ion-dipole interaction with water is T13+ than Cd²+ than Na+.

An ion-dipole interaction is defined as the intermolecular force of attraction present between the charged ion (anion or cation) and the molecule. It is mainly found in the solution where the ionic compounds dissolved in the polar solvents.

The strength of ion-dipole interactions is mainly dependent on the distance and the charge. Ionic charge goes on increasing moving across a period on the periodic table.

Since, charge on Ti is 3 and greater than Cd which is greater than Na.

Thus, we concluded that the strongest ion-dipole interaction with water is T13+ than Cd²+ than Na+.

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The two of these elements are the least reactive are (c) Copper Cu and (f) Mercury Hg.

Elements in lower left and in the upper right of the periodic table are the most reactive, except noble gases which are very un-reactive because they are stable. we can also used the reactivity series or activity series of metal to ans this.

On the periodic table the least reactive elements are the transition metals which are placed in middle of the periodic table.the elements Potassium K and Rubidium Rb are the alkali metals and are reactive.the elements Chlorine Cl and Barium Ba are the alkaline metals and are reactive metals.The  Elements Copper Cu, and Mercury Hg are placed in the middle of the periodic table and are least reactive.

Thus,The two of these elements are the least reactive are (c) Copper Cu and (f) Mercury Hg.

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