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olga2289 [7]
3 years ago
13

Help pls!!

Chemistry
1 answer:
ankoles [38]3 years ago
7 0

Answer:

C, physical change

Explanation:

take a look at the equation. Next to each form of water do you see the little (g) and (l)? These represent the state of matter the water is in. So, the water is going from a gas to a liquid. The chemical compound is the same so its a physical change, not chemical, and it is reversible. You could change the liquid water back to the gas through evaporation. Endothermic has literally nothing to do with this equation so you can easily eliminate that answer choice.

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How are fossils formed
creativ13 [48]
I am sure the answer is D
7 0
4 years ago
Reaction 1: Solid sodium hydroxide dissolves in water to form an aqueous solution of ions. ????????????H(????) → ????????+(?????
Dennis_Churaev [7]
Hi, here is a basic summary of what we did in a lab; there were 3 reactions: The procedure: Reaction 1: Solid sodium hydroxide dissolves in water to form an aqueous solution of ions. NaOH(s)-> Na+(aq) + OH-(aq) ΔH1=-34.121kJ Reaction 2: Solid sodium hydroxide reacts with an aqueous solution of HCl to form water and an aqueous solution of sodium chloride. NaOH(s) + H+(aq) + Cl-(aq) -> H2O + Na+(aq) + Cl-(aq) ΔH2=-83.602kJ Reaction 3: An aqueous solution of sodium hydroxide reacts with an aqueous solution of HCl to form water an an aqueous solution of sodium chloride. H+(aq) + OH-(aq) + Na+(aq) + Cl-(aq) -> H2O + Na+(aq) + Cl-(aq) ΔH3= -50.2kJ The ΔH values were calculated by dividing the heat gained by the number of moles (each reaction had 0.05moles of NaOH) The problem: Net ionic equations for reaction 2 & 3: 2: NaOH(s) + H+(aq) -> H2O + Na+(aq) 3: H+(aq) + OH-(aq) -> H2O i) In reaction 1, ΔH1 represents the heat evolved as solid NaOH dissolves. Look at the net ionic equations for reactions 2 and 3 and make similar statements as to what ΔH2 and ΔH3 represent. ii) Compare ΔH2 with (ΔH1 + ΔH3). Explain in sentences the similarity between these two values by using your answer to #5 above. Attempt at answering: i) Firstly, ΔH2 represents the heat evolved as the hydrogen ion displaces the sodium ion, creating a single displacement reaction. ΔH3 represents the heat evolved as the hydrogen and hydroxide ion form water via a neutralization reaction. ii) ΔH2 is equal to (or supposed to be, this is a source of error while calculating) (ΔH1 + ΔH3). The similarity between these two values is that .. (this is where I get confused!)

Source https://www.physicsforums.com/threads/calorimetry-help-chemistry.399653/
5 0
3 years ago
Assuming an electron is a hydrogen atom can undergo any of the transitions below, thus changing its energy. Which transition is
inn [45]

Answer:

n = 3 to n = 5

Explanation:

According to the Bohr's model of the atom, electrons in an atom absorb energy to move from a lower to higher energy level.

We must note that as we progress away from the nucleus, the energy levels of electrons become closer together. The energy difference between successive levels decreases and the wavelength of light associated with such transitions become longer.

Hence,the absorption of light of the longest wavelength corresponds to n = 3 to n = 5

.

5 0
3 years ago
A chemist wants to observe the following reaction:
stiv31 [10]

It take more energy to break the bonds of the reactants and less energy is given off when the product bonds are formed.

<h3>What is Energy?</h3>

Energy is defined as the ability to do work. Work is done in the breaking or formation of bonds.

The standard Enthalpy (ΔH) of water which was formed in the given reaction is negative.

ΔH= Δproduct - Δreactant

This means that the energy to break the bonds of the reactants is more.

Read more about Enthalpy here brainly.com/question/14291557

3 0
2 years ago
Which force controls the size of an atomic nucleus?.
klemol [59]

Answer:

strong nuclear force

Explanation:

1, a force that acts on charged particles

2, a force that holds atomic nuclei together

3, gravity, weak nuclear, electromagnetic, strong nuclear

4, strong nuclear force

5, Gravity and the electromagnetic force have infinite ranges while the nuclear forces have very small ranges.

100% :)

3 0
2 years ago
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