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3 years ago

If gold gets hot enough it will melt, what type of change is this?

Chemistry

2 answers:

SashulF [63]3 years ago

8 0

A.
Physical change
Step by step explanation;:)

Lynna [10]3 years ago

6 0

Answer:

A) Physical

Explanation:

Melting is a physical change, not a chemical change.

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If 1.27 moles of bromine gas (Br2) react with excess phosphorus (P), how many moles of phosphorus tribromide (PBr3) will be prod

frez [133]

Answer:

0.85 mole of PBr3.

Explanation:

We'll begin by writing the balanced equation for the reaction. This is given below:

3Br2 + 2P —> 2PBr3

From the balanced equation above,

3 moles of Br2 reacted to produce 2 moles of PBr3.

Therefore, 1.27 moles of Br2 will react to produce = (1.27 x 2)/ 3 = 0.85 mole of PBr3.

Therefore, 0.85 mole of PBr3 is produced by the reaction.

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3 years ago

Based on the article "Will the real atomic model please stand up?,” describe what Dalton’s theory states about a molecule of wat

Ira Lisetskai [31]

Answer:

water is made of 2 hydrogen atoms bonded by 1 oxygen atom

Explanation:

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3 years ago

Read 2 more answers

Write an equation that expresses the law of thermodynamics in terms of heat and work

Anettt [7]

We write DE = q+w, where DE is the internal energy change and q and w are heat and work, respectively.

(b)Under what conditions will the quantities q and w be negative numbers?

q is negative when heat flows from the system to the surroundings, and w is negative when the system does work on the surroundings.

As an aside: In applying the first law, do we need to measure the internal energy of a system? Explain.

The absolute internal energy of a system cannot be measured, at least in any practical sense. The internal energy encompasses the kinetic energy of all moving particles in the system, including subatomic particles, as well as the electrostatic potential energies between all these particles. We can measure the change in internal energy (DE) as the result of a chemical or physical change, but we cannot determine the absolute internal energy of either the initial or the final state. The first law allows us to calculate the change in internal energy during a transformation by calculating the heat and work exchanged between the system and its surroundings.

3 0

4 years ago

In general, as you move from right to left across a period, the number of valence electrons

goblinko [34]

As you move from left to right across a period,the number of valence electrons-increases.

4 0

3 years ago

Read 2 more answers

When 60 mL of 0.22 M NH4Cl is added to 60 mL of 0.22 M NH3, relative to the pH of the 0.10 M NH3 solution the pH of the resultin

densk [106]

Answer:

Will be more acidic

Explanation:

The equilibrium of NH3 in water is:

NH3(aq) + H2O(l) ⇄ NH4⁺(aq) + OH⁻(aq).

Where equilibrium constant, Kb, is:

Kb = 1.85x10⁻⁵ = [NH4⁺] [OH⁻] / [NH3]

From 0.10M NH3, the reaction will produce X of NH4⁺ and X of OH⁻ and Kb will be:

1.85x10⁻⁵ = [X] [X] / [0.10M]

1.8x10⁻⁶ = X²

X = 1.34x10⁻³ = [OH⁻]

As pOH = -log[OH⁻] = 2.87

And as pH = 14 - pOH

pH of the 0.10M NH3 is 11.13

Now, to find the pH of the NH4Cl and NH3 we need to use H-H equation for bases:

pOH = pKb + log [NH4⁺] / [NH3]

Where pKb is -log Kb = 4.74 and [] are moles of both compounds.

Moles of [NH4⁺] = [NH3] = 60mL, 0.060L*0.22M = 0.0132moles:

pOH = 4.74 + log [0.0132] / [0.0132]

pOH = 4.74

pH = 14 - 4.74 = 9.26

That means the pH of the resulting solution will be more acidic

7 0

3 years ago