newsela what is a chemical reaction

Answer:

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NH3 has 1 Nitrogen atom and 3 hydrogen atoms.

Answer:

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Explanation:

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In toxicology, the median lethal dose, LD₅₀, LC₅₀ or LCt₅₀ is a measure of the lethal dose of a toxin, radiation, or pathogen. The value of LD₅₀ for a substance is the dose required to kill half the members of a tested population after a specified test duration.

Answer:

To find the pOH, simply subtract the pH from 14. In order to calculate the pOH, take the negative log of the hydroxide ion concentration.

Answer:

14...................

Answer:

A) BaCl2 + 2NaOH → Ba(OH)2 + 2NaCl

B) H2SO4 + 2KOH → K2SO4 + H2O

C) K2O3 + 2HCl → 2KCl + H2O + CO2

D) 2FeSO4 → Fe2O3 + SO2 + SO3

E) 2NaNO3 → 2 NaNO2 + O2

Explanation:

Answer:

A) BaCl² + 2NaOH → _Ba(OH)² + 2NaCl

B) H²SO⁴ + 2KOH → _K²SO⁴ + H²O

C) K²CO³ + 2HCl → _KCl + H²O + CO²

D) 2FeSO⁴ → _Fe²O³ + _SO² + _SO³

E) 2NaNO³ → 2NaNO² + _O²

Answer:

the answer is harmed

Explanation:

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Considering the ideal gas law, when pressure, volume, and temperature of a gas are known the ideal gas law can be used to calculate the number of moles (option c).

An ideal gas is a theoretical gas that is considered to be composed of randomly moving point particles that do not interact with each other. Gases in general are ideal when they are at high temperatures and low pressures.

An ideal gas is characterized by three state variables: absolute pressure (P), volume (V), and absolute temperature (T). The relationship between them constitutes the ideal gas law, an equation that relates the three variables if the amount of substance, number of moles n, remains constant and where R is the molar constant of gases:

Being R the molar constant of gases, when pressure, volume, and temperature of a gas are known the ideal gas law can be used to calculate the number of moles (option c).

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Answer:

Explanation:

When workers stop working entirely, it is called either a strike or retirement, depending on the circumstances under which it is done.  A strike is a mass refusal of employees to work, because they are not satisfied.  

Retirement on the other hand happens when the employee reaches certain age, after which he/she can leave the job and get a pension,.

Answer: (d)-Silver

Explanation:

Given

The mass of sample is [tex]m=18\ gm[/tex]

It is heated from [tex]21.5^{\circ}C[/tex] to [tex]89^{\circ}C[/tex]

heat energy absorbed is [tex]292\ J[/tex]

Heat absorbed is given by [tex]Q=mc\Delta T[/tex]

Insert the values

[tex]\Rightarrow 292=18\times c\times [89-21.5]\\\Rightarrow 292=18\times c\times 67.5\\\\\Rightarrow c=\dfrac{292}{1215}\\\\\Rightarrow c=0.24\ J/g^{\circ}C[/tex]

As per the table, it is Silver

Answer:

5

Explanation:

Answer:

Hydrologists study how water interacts with the earth's crust. For example, they may study how rainfall and snowfall cause erosion, create caves, percolate through soil and rock to become groundwater, or eventually reach the sea.Hydrologists strive to improve water quality and increase our access to water so that we can continue to make use of it in all the ways that are necessary to our lives. A hydrologist measures the stream flow in a tributary to the Coeur d'Alene River. layers of gases surrounding a planet or other celestial body

Answer:

12.7 L (3 s.f.)

Explanation:

Since it is an ideal gas, we can apply the ideal gas law:

[tex]\boxed{pV=nRT}[/tex]

☆ where p= pressure

V= volume

n= number of moles

R= ideal gas constant

T= temperature

Substitute all the given information into the formula:

2V= 1(0.08206)(310)

2V= 25.4386

V= 25.4386 ÷2

V= 12.7 L (3 s.f.)

Further explanation:

The ideal gas constant, R, has different values depending on what units are being used. Two examples are listed below:

[tex]• \: 0.08206 \: L \: atm ^{ - 1} \: mol \: K[/tex]

[tex]• \: 8.314 \: J \: {mol}^{ - 1} \: {K}^{ - 1} [/tex]

In the above question, we use the value 0.08206 because the pressure was given in atm and the temperature was given in Kelvin. Thus, the unit used for volume is L.

Answer: 12.7 L

Explanation:

P=2.0atm

V= ???

n=1.0 mol

R= 0.0821

T= 310K

PV=nRT--> (2)V=(1)(0.0821)(310)

                     V=12.7 L

Answer:

The correct answer is B, "Specific heat capacity of the substance."

Explanation:

I just took the test. I hope this helps!

Heat absorbed changes the bonds of the molecules or the compounds to alter their state. The specific heat capacity affects the amount of heat absorbed. Thus, option B is correct.

Specific heat capacity is defined as the amount of heat or energy absorbed by the kilogram of the solid reactant when the system experiences a rise in temperature. It is measured in J/(kg K) or J/(kg °C).

The specific heat capacity, the mass of the substance, temperature, and the phase of the substance affects the absorption of the heat from the surrounding. The specific heat affects absorption as it tells about the substance's ability to take the heat energy.

Therefore, specific heat capacity affects heat absorption.

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Answer:

Two alpha particle decays and one beta particle decay.

Explanation:

If Lead Pb-207 is to turn into Gold, Au-199, there needs to be a drop in mass number from 207 to 199. That drop is 207 - 199 = 8.

Since the mass number of an alpha particle(⁴₂He) is 4, to lose 8 nuclear particles(neutron + proton), we need 8 particles/nucleus ÷ 4 particles per alpha particle nucleus = 2 alpha particles.

The nuclear equation is given below

²⁰⁷₈₂Pb → ¹⁹⁹₇₉Au + ⁴₂He + ⁴₂He

Note that the charge is not balance

82 ≠ 79 + 2 + 2 = 83

For this to be balanced, we need to lose a beta particle, ⁰₋₁e. So, our equation becomes

²⁰⁷₈₂Pb → ¹⁹⁹₇₉Au + ⁴₂He + ⁴₂He + ⁰₋₁e

So, series of decays would allow you to turn Lead, Pb-207 into Gold, Au-199 are two alpha particle decays and one beta particle decay.

Answer:

P

1

V

1

T

1

=

P

2

V

2

T

2

Explanation:

P

1

V

1

T

1

=

P

2

V

2

T

2

, given a constant quantity of gas.

And thus,  

P

1

×

V

1

×

T

2

V

2

×

T

1

=

P

2

, even given this format, we can see the problem is dimensionally sound. We do need to use  

absolute temperature.

P

2

=

1.00

⋅

a

t

m

×

250

⋅

m

L

×

313

⋅

K

500

⋅

m

L

×

293

⋅

K

≅

1

2

⋅

a

t

m

.

Explanation:

Answer:

An environment is a local area of living creatures existing related to the nonliving segments of their current circumstance, interfacing as a framework. These biotic and abiotic segments are connected together through supplement cycles and energy streams.

Explanation:

Answer:

Living organisms require a proper, stable ecosystem/envirornment to function

Explanation:

Answer:

Pollution

Overpopulation

Destruction of habitats

Explanation:

Answer:

The correct option is (a) "0.92 V".

Explanation:

The voltage of a galvanic cell made with zinc (Zn) and aluminum (AI) is given by :

Voltage =Ered- Eoxd

Where

Ered = reduction potential

Eoxd = oxidation potential

As per reduction standard potentials, the emf of Zinc is -0.76 V  and the emf of Aluminium is -1.66 V. So,

V = 0.76 - (-1.66)

= 0.9 V

Hence, the correct option is (a) "0.92 V".

Answer:

When one reactant is in excess, there will always be some left over. The other reactant becomes a limiting factor and controls how much of each product is produced. While using excess reactants can help to increase percentage yields, this is at the expense of atom economy.

Explanation:

Answer:

Density is the total number of particles in a given volume

Explanation:

As per the particle theory, density is defined as total space occupied by certain number of particles of any given element with in a defined volume is termed as density.

Density is not the denseness of a single unit but the space occupied by many single units with in a given volume V

Hence, density is the total number of particles in a given volume.

Answer:

nucleus

Explanation:

Answer:

Found in the nucleus

Explanation:

I hope this answer is correct and helpful!

Any molecule can be represented by a formula that lists all the atoms in that molecule. Each element is represented by its atomic symbol in the Periodic Table – e.g. H for hydrogen, Ca for calcium. If more than one atom of a particular element is present, then it’s indicated by a number in subscript after the atomic symbol — for example, H2O means there are 2 atoms of hydrogen and one of oxygen.

If there is more than one of whole groups of atoms, then that’s shown with a bracket around them. For example, calcium hydroxide has one calcium (Ca) for every two hydroxides (OH), so is written as Ca(OH)2.

If a charge is present, it’s indicated in superscript, with a sign (+/-) and a number if more than one charge is present. For example, calcium ions have two positive charges so are written Ca2+.

Sometimes a formula can be written in a way that gives an indication of the structure. A chemical equation shows a reaction taking place. On the left-hand side are the reactants, the molecules that take part in the reaction. On the right-hand side are the products, the molecules that are created in the reaction. Each side must contain the same number of each kind of atom. An arrow between them indicates the direction the reaction is expected to occur:

Ca + Cl2 → CaCl2

Calcium + chlorine → Calcium chloride

If there are two or more of any molecules, that’s indicated with a number in front of the molecule:

CH4 + 2O2 → CO2 + 2H2O

One methane molecule + two oxygen molecules → one carbon dioxide molecule and two water molecules

An equation may sometimes specify which phase each molecule is in – whether it’s solid, liquid, or gas, or if it’s dissolved. This is written in brackets after the molecule – (s) for solid, (l) for liquid, (g) for gas, and (aq) for ‘aqueous’, meaning dissolved in water. For example, solid calcium carbonate reacts with carbonic acid in water to form calcium bicarbonate, which is much more soluble so becomes dissolved in water:

CaCO3 (s) + H2CO3 (aq) → Ca(HCO3)2 (aq)

Solid calcium carbonate + dissolved carbonic acid → dissolved calcium bicarbonate

All chemical reactions can actually proceed in either direction. Most of the time, one direction is expected to take place more strongly, so the arrow is written in that direction. However, many common reactions happen in both directions simultaneously, creating an equilibrium where the reactions are taking place but there is no net change in concentration from one side to the other. This is indicated with the symbol ⇌.

For example, carbonic acid in water is continually breaking down into bicarbonate and hydrogen ions – but the ions are also continually joining back together.

H2CO3 ⇌ HCO3– + H+

Carbonic acid ⇌ bicarbonate + hydrogen ions

Answer: 0.84g

Explanation: