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3 years ago

Select the equations below that represent physical changes.

1 answer:

6 0

Physical changes- any change in the physical properties of the substance is a physical change. Generally physical properties include color, state, size , shape, odour, appearance . In any phyical change, no new substance is formed.

Chemical changes- any change in the chemical properties of the substance is a chemical change. Chemical properties changes only when something new is formed during a reaction.

∴ Part A- 2 H2O(l) → 2 H2(g) + O2(g)

In this, H2 and O2 is produced during the reaction which is different from H20. Thus, it is a chemical change.

Part B- H2O(l) → H2O(s)

In this, only the state of water changes from liquid to solid and no new product is formed. Thus, it is a physical change.

Part C-CO2(s) → CO2(g)

In this also, only the state of CO2 changes from solid to gas and no new product is formed. Thus, it is a physical change.

Part D-H2(g) → 2 H(g)

In this reaction, H2 molecule is dissociated into 2 hydrogen atom leading to formation of new products. Thus, it is a chemical change.

Finally, equations that represent physical changes are - B and C

B. H2O(l) → H2O(s)

C. CO2(s) → CO2(g)

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To determine the concentration of SO4 2– ion in a sample of groundwater, 100.0 mL of the sample is titrated with 0.0250 M Ba(NO3

Brrunno [24]

Answer:

1.87x10⁻³ M SO₄²⁻

Explanation:

The reaction of SO₄²⁻ with Ba²⁺ (From Ba(NO₃)₂) is:

SO₄²⁻(aq) + Ba²⁺(aq) → BaSO₄(s)

Where 1 mole of SO₄²⁻ reacts per mole of Ba²⁺

To reach the end point in this titration, we need to add the same moles of Ba²⁺ that the moles that are of SO₄²⁻.

Thus, to find molarity of SO₄²⁻ we need to find first the moles of Ba²⁺ added (That will be the same of SO₄²⁻). And as the volume of the initial sample was 100mL we can find molarity (As ratio of moles of SO₄²⁻ per liter of solution).

Moles Ba²⁺:

7.48mL = 7.48x10⁻³L ₓ (0.0250moles / L) = 1.87x10⁻⁴ moles of Ba²⁺ = Moles of SO₄²⁻

Molarity SO₄²⁻:

As there are 1.87x10⁻⁴ moles of SO₄²⁻ in 100mL = 0.1L, molarity is:

1.87x10⁻⁴ moles of SO₄²⁻ / 0.1L =

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3 years ago

Identify each type of bond:

zloy xaker [14]

Answer:

The type of bond between the Oxygen atom and the hydrogen is Covalent

this is because the 2 electrons are being shared by both hydrogen and oxygen

The type of bond this molecule makes as a whole is called a Hydrogen Bond

A hydrogen bond is formed because of the partial +ve and -ve charge in a molecule

The cause of the partial +ve and -ve charge is the comparatively high electronegativity of oxygen which makes the electron get attracted towards the oxygen atom while the hydrogens try to maintain the maximum distance from the lone pairs due to repulsion

Hope it helped

Kindly Mark Brainliest

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3 years ago

Based on the current atomic theory most chemical reaction take place as a result of the interactions of which sub- atomic partic

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Electrons, everything is pretty much based around the likeliness of electrons to be swapped or shared between atoms

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3 years ago

Look at this compound, why does magnesium has dative and covalent bonds with nitrogen? ...?

HACTEHA [7]

The solid lines between N and Mg are actually ionic bonds. N has 5 valence electrons (2 of which are paired). Of the 3 that are unpaired, 2 are part of covalent bonds with adjacent carbon atoms. N accepts an extra electron to complete its octet, but gets a formal charge of -1. This allows for formation of an ionic bond with Mg, which is +2. Two of these charged N atoms therefore neutralize the charge of the central Mg. As for the coordinate (dative) covalent bonds, Mg has empty orbitals - the ionic bonds with the charged N atoms give it only 4/8 possible valence electrons.

The other two N atoms (dotted lines) have a formal charge of 0 since they form three covalent bonds with adjacent carbon atoms, but they still have a lone pair. Therefore, just to improve stability, each of these N atoms can "donate" its lone pair to Mg in order to complete its octet.

I hope my answer has come to your help. Thank you for posting your question here in Brainly. We hope to answer more of your questions and inquiries soon. Have a nice day ahead!

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4 years ago

What is the mass of a neutron? 1/2,000 amu 1 amu 2,000 amu 1/200 amu

pashok25 [27]

Vas happenin!!

1 amu is the correct answer

Hope this helps

-Zayn Malik

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3 years ago

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