How to tell if a reaction is exothermic.

Answers

Answer 1

Answer:

If the reaction loses heat it is exothermic.

Answer 2
If the enthalpy change listed for a reaction is negative, then that reaction releases heat as it proceeds — the reaction is exothermic (exo- = out). If the enthalpy change listed for the reaction is positive, then that reaction absorbs heat as it proceeds — the reaction is endothermic (endo- = in).

Related Questions

Which element has 12 protons 12 neutrons and 12 electrons

Answers

Answer:

Magnesium

Explanation:

Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray solid which bears a close physical resemblance to the other five elements in the second column of the periodic table: all group 2 elements have the same electron configuration in the outer electron shell and a similar crystal structure.







Q. What phase change occurs at letter A?

Answers

Answer:

Where is the picture? Can't answer without it.

Part 1. After learning about the different parts and functions of a meroscope you will now reflect on the importance of ench part citeit significance of each parts by naming it and answering the guide question​

Answers

Explanation:

after learning more about the position and would

Give 2 reason why cryolite is used

Answers

two reasons why cryolite is used in the electrolysis of aluminium oxide. The mixture of cryolite and aluminium oxide has a lower melting point than pure aluminium oxide. This means a lower amount of energy is required to establish effective conditions for electrolysis and thus makes it more cost effective.

Give two reasons why cryolite is used in the electrolysis of ...https://www.mytutor.co.uk › answers › GCSE › Chemistry

The flow of current is always in what direction

Answers

Answer:

The direction of an electric current is by convention the direction in which a positive charge would move. Thus, the current in the external circuit is directed away from the positive terminal and toward the negative terminal of the battery.

Explanation:

Answer:

Electrons always flow in opposite directions. The direction of an electric current is by convention the direction in which a positive charge would move. Electric current flows from higher electric potential to lower electric potential.

Explanation:

What is the mass of oxygen atoms in 0. 380 mol fe(co)5?.

Answers

Answer:39+30

Explanation:

How is heat transferred when a person holds a pen that is already at body
temperature?
A. From the hand to the pen
B. Heat is not transferred.
C. In both directions between the pen and the hand
D. From the pen to the hand
SUBMIT

Answers

Answer:

The answer is B.

Explanation:

Heat is not transferred.

How many valence electrons does aluminum have.

Answers

Answer:

3 valence electrons

Explanation:

Aluminum has three valence electrons. Valence electrons are found in the outermost shell of an element and are responsible for its valence.

A 250. mL sample of oxygen is collected over water at 25 °C and 760.0 torr pressure. What is the partial pressure
of the oxygen? (Vapor pressure of water at 25°C is 23.8 mm Hg)

Answers

Answer:The mass of oxygen gas sample collected over water is 0.544 g.

The given parameters;

temperature of the oxygen gas, t = 25 °C

total pressure of the gas, P = 644 torr

volume of the gas, V = 500 mL

vapor pressure = 23.8 torr

molar mass of oxygen gas = 32 g/mol

The number of moles of the gas collected is calculated by using ideal gas equation as follows;

PV = nRT

where;

R is the ideal gas constant = 62.36 L.torr/mol.K

P is the pressure of the gas = 644 torr - 23.8 torr = 620.2 torr

T is the temperature of the gas = 25 + 273 = 298 K

V is the volume of the gas = 500 mL = 0.5 L

The number of moles of the  gas is calculated as follows;

The mass of oxygen gas collected is calculated as follows;

m = 0.017 (32 g/mol)

m = 0.544 g

Thus, the mass of oxygen gas sample collected over water is 0.544 g.

Explanation:

The partial pressure of oxygen is; 760.0 torr - 23.8  torr = 736.2 torr.

What is partial pressure?

We know that in a mixture of gases, the pressure that is exerted by each gas is called the partial pressure of the mixture.

In this case, we have the total pressure of the mixture as 760.0 torr and the vapor pressure of water as 23.8 mm Hg or 23.8  torr) at that temperature. Hence, the partial pressure of oxygen is; 760.0 torr - 23.8  torr = 736.2 torr.

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A fusion reaction always creates which of the following?

a A massive amount of energy.
b A massive amount of heat.
C A more massive atomic nucleus.
d A massive number of smaller nuclei.

Answers

A fusion reaction can be regarded as the type of reaction that occurs where two lighter elements come together in a type of reaction giving rise to a heavier/more massive element.

A fusion reaction always creates a more massive atomic nucleus (option c).

When the two lighter nuclei comes together in a reaction, a more heavier/massive nucleus is formed but its mass will still be less than the combined mass of the two reactant nuclei.

This also indicates that the left over mass may have been released as energy.

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Could someone take a picture of an acid or a base and label them

Answers

Answer:

Ok

Explanation:

Help please, take a screenshot who will answer will be brainiest.

Answers

Answer:

1:

•a typical metal tends to have a higher melting and boiling point than a typical non metal which has a low melting and boiling point

•a typical metal tends to have a shiny appearance than a typical non metal which has a dull apearance

•and finally, a typical metal is a good conductor of electricity and heat while a typical non metal isn't

2:

elements E and C

3:

a, it doesn't conduct electricity

b, it's a good conductor of heat/ has a high melting point/ has a high boiling point (you can choose either that sits right with you)

Why cathode rays have reducing effect

Answers

Answer:

Cathode rays consist mainly of electrons, they ionize substance, this leads to reduction. Any ions produced are collect by an ion trap in the tube therefore anything the beam of electrons hits is going to gain electrons.

How to find the partial pressure of a gas.

Answers

Answer:

The total pressure of a mixture of gases can be defined as the sum of the pressures of each individual gas: Ptotal=P1+P2+… +Pn. + P n . The partial pressure of an individual gas is equal to the total pressure multiplied by the mole fraction of that gas.

Using diving terms, partial pressure is calculated as: partial pressure = (total absolute pressure) × (volume fraction of gas component) For the component gas "i": pi = P × F.

How many grams of zinc chloride could be formed from the reaction of 3. 57g zinc with excess hcl?.

Answers

Zn+2HCl = ZnCl2 + H2
Zn= ZnCl2
65.38g Zn= 136.315 g ZnCl2
1g Zn = 136.315/65.38 g ZnCl2
3.57 g Zn = (136.315/ 65.38) × 3.57 g of ZnCl2
3.57g Zn = 7.443g ZnCl2

the atomic number of RE is 75. the atomic mass of one of its isotopes is 186. how many neutrons are in an atom of this isotopes

Answers

Answer:

111

Explanation:

Answer:

I believe Rhenium has 111 neutrons in the atoms isotopes.

Explanation:

ignore q above 6 NO LINKS and please answer all question 6-9 and parts ​

Answers

Where is the question?

Write the symbol for the atom with 38 protons, 36 electrons, and 50 neutrons and identify the element.

Answers

Answer:

Symbol: Sr2+

Element: Strontium

Explanation:

Strontium will have 38 protons, 38 electrons, and the neutron will depend on the isotope but there will usually be 48, 49, or 50 neutrons

Hope this Helps

What are the two ways in which cellular processes can be regulated?

Answers

Answer:

Homeostasis to photosynthesis and anaerobic respiration to aerobic respiration.

Name the method that used to separate the components of petroleum oil.

Answers

Answer:

fractional distillation

Explanation:

How many atoms of each element are in NaCI?


Enter your answer in the boxes:

|___| sodium

|___| chlorine

Answers

Answer:

well first you need 1 s then you need 1 ch

Explanation:

Which of these elements would have an electron affinity higher than that of oxygen?


Li
Ca
Ne
C
Be

Answers

Answer: Ne ( Neon )

Explanation: Lithium ( Li ), beryllium ( Be ), carbon ( C ), oxygen ( O ), and neon ( Ne ), are all in Period 2 in that order. Sodium ( Na ) is in Period 3. Since electron affinities decrease as you go down, Na would have a lower electron affinity level then Li but since electron affinities increase as you go across a period, only neon is farther right then oxygen ( O ), so it would be the only one element of this group that would have a higher electron affinity than that of oxygen.

There are various kind of elements that are present in periodic table. Some elements are harmful, some are radioactive, some are noble gases. Option C is correct option.

What is periodic table?

Periodic table is a table in which we find elements with properties like metals, non metals, metalloids and radioactive element arranges in increasing atomic number.

Periodic table help a scientist to know what are the different types of elements are present in periodic table so that they can discover the new elements that are not being discovered yet.

On going down the group electronegativity decreases. On going along the period the electronegativity increases. So, Neon lies on the extreme right of Fluorine in the same period. Neon will have more electronegativity than oxygen.

Therefore, Neon is more electronegativity than fluorine.

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When pyridine is treated with a mixture of nitric and sulfuric acids, the major product is:.

Answers

Answer: 3-nitropyridine

Explanation:

Do distilled water conduct electricity what will happen if we add sugar to it and then salted

Answers

Answer:

No, distilled water does not conduct electricity.If we were to add sugar then it will not conduct electricity, but if we were to add salt though it would conduct electricity.

Explanation:

why are 35 17 cl bad 37 17 cl isotopes of the element of chlorine? ​

Answers

Answer:

Chlorine-35 and chlorine-37 are not different elements because an atom of chlorine-35 and an atom of chlorine-37 each contain the same number of protons. The number of protons an atom has, also known as the atom's atomic number, determines which element it is. All atoms which contain 17 protons are called chlorine atoms. Adding or removing a proton from an atom's nucleus changes that atom's atomic number and creates a different element.

Chlorine-35 and chlorine-37 are both isotopes of the element chlorine. The number after the name 'chlorine' is called the mass number. The mass number is a tally of the number of protons and the number of neutrons in an atom's nucleus. Since all atoms of chlorine contain 17 protons, chlorine-35 and chlorine-37 differ in the number of neutrons each one has. An atom of chlorine-35 contains 18 neutrons (17 protons + 18 neutrons = 35 particles in the nucleus) while an atom of chlorine-37 contains 20 neutrons (17 protons + 20 neutrons = 37 particles in the nucleus).

Adding or removing a neutron from an atom's nucleus creates isotopes of a particular element. Why does changing the number of protons in an atom change which element that atom is but changing the number of neutrons doesn't? Protons carry a positive charge. Each proton in an atom's nucleus must be balanced with a negatively charged electron in one of the 'shells' outside the nucleus. The number of electrons in an atom's outer shell determines the atom's chemical properties. Adding or removing protons changes the number and arrangement of electrons in the outer shell which changes how that atom reacts with other atoms. Neutrons don't change things greatly because they do not carry an electrical charge. Neutrons can be added or removed from an atom and the electrons around the atom really don't care that much.

What is the correct formula for tetraphosphorous octaoxide
P4O10
P4O8
Ph4O8
P5O8

Answers

P_4O_8

How?

Let's learn how to create name of compound from its name.

Look below for root words

2-di 3-tri4-tetra5-pent6-hex7-hept8-oct9-non10-dec

Hence formula of the compound is P4O8

How do mixtures differ from substances?

Answers

Answer:

In chemistry: a pure substance consists only of one element or one compound. a mixture consists of two or more different substances, not chemically joined together.

Hope this helps :)

Given that E°red = -0.40 V for Cd2+/Cd at 25°C, find E° and E for the concentration cell expressed using shorthand notation below.

Cd(s) ∣ Cd2+(1.0 × 10-5 M) ∣∣ Cd2+(0.100 M) ∣ Cd(s)

E° = 0.00 V and E = +0.12 V


E° = 0.00 V and E = +0.24 V


E° = -0.40 V and E = -0.16 V


E° = -0.40 V and E = -0.28 V

Answers

From the information in the question, the   and E for the cell is 0.00 V and 0.12 V.

Using the Nernst equation;

Ecell =  E°cell - 0.0592/n log Q

We know that  E°cell = 0.00 V since the anode and cathode are both made up of cadmium.

Substituting the given values into the Nernst equation;

Ecell = 0.00 V - 0.0592/2 log (1.0 × 10-5 M/0.100 M)

Ecell =  0.00 V - 0.0296 log(1 × 10^-4)

Ecell = 0.12 V

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how can teh human body looose heat? (conduction, convecion, radiation) and WHY

Answers

Answer:

Radiation and conduction

Explanation:

The human body lose heat by these two ways, because everything that touches our bodies and is in a temperature below us will receive part of our heat (conduction), and you can figure out that we lose heat by radiation because a human bright in a heat cam

which of these is a rough approximation of the cogito?

Answers

Given the Latin meaning of the cogito, we can confirm that it is roughly translated and summarized by the phrase "I think, therefore I am".

Cogito, ergo sum or "The Cogito" is an extremely popular, well-known philosophical phrase credited to Rene Descartes. This Latin phrase is roughly translated as "I think, therefore I am", which appeared originally in "The Principles of Philosophy", and was later translated to a variety of languages in an attempt to reach a wider public, most notably into Latin.

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