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Step2247 [10]
3 years ago
8

A long stairway with a metal handrail runs between the houses of Amelia and her friend Michelle. After getting their parents' pe

rmission, the two girls often play near the stairs. One day, Michelle stands at the top of the steps and taps the railing with a stone. Amelia stands at the bottom of the steps with her right ear pressed against the railing.
Amelia sees Michelle tap the railing, then she hears the sound with the ear that is pressed against the railing. Last, Amelia hears the sound with her other ear. Why did Amelia hear the sound with her right ear before her left ear?
A.
because light travels more quickly through air than sound does
B.
because the particles that carry sound energy travel more quickly through solids than through gases
C.
because the waves that carry sound energy travel more quickly through solids than through gases
D.
because her right ear was closer to Michelle, who was the source of the sound

PLEASSSSSE HEEELLPPP MMMMEEEE
Chemistry
2 answers:
Ahat [919]3 years ago
5 0

Answer:

D.

because her right ear was closer to Michelle, who was the source of the sound

jasenka [17]3 years ago
5 0

Answer:

because the waves that carry sound energy travel more quickly through solids than through gases

Explanation:

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Write the balanced chemical equation for the following reaction. Phases are optional. Solid calcium chlorate decomposes to form
Tanya [424]

Answer:

  • Ca(ClO₃)₂ (s) → CaCl₂ (s) + 3O₂ (g)

Explanation:

1)<u> Word equation (given)</u>

  • <em>calcium chlorate (solid) → solid calcium chloride (solid)  + oxygen (gas)</em>

2) <u>Chemical formulae of the reactant and products</u>:

  • <em><u>Calcium chlorate</u></em><em>: </em>

The most common oxidation states of chlorine are -1, +1, +3, +5, +7.

The suffix ate in chlorate means that chlorine atom is with the third lowest oxidation state (counting only the positive states). So, this is +5.

The oxidation state of calcium is +2.

Hence, the chemical formula of calcium chlorate is Ca(ClO₃)₂

  • <u><em>Calcium chloride</em></u>

The suffix ide in chloride means that chlorine is with oxidation state -1. Again the oxidation state of calcium is +2.

Hence, the chemical formula of calcium chloride is CaCl₂

  • <u><em>Oxygen</em></u>

Oxygen gas is a diatomic molecule, so its chemical formula is O₂.

  • <u><em>Phases</em></u>

The symbols s and g (in parenthesis) indicate the solid and gas phases respectively.

3) <u>Chemical equation</u>:

  • Ca(ClO₃)₂ (s) → CaCl₂ (s) + O₂ (g)

That equation is not balanced becasue the number of O atoms in the reactant side and in the product side are different.

4)<u> Balanced chemical equation:</u>

Add a 3 as coefficient in front of O₂(g), in the product side to balance:

  • Ca(ClO₃)₂ (s) → CaCl₂ (s) + 3O₂ (g)

Verify that all the atoms are balanced:

Atom    Reactant side      Product side

Ca             1                           1

Cl              2                          2

O              3×2 = 6                2×3 = 6

Conclusion: the equation is balanced and the final answer is:

  • Ca(ClO₃)₂ (s) → CaCl₂ (s) + 3O₂ (g)
5 0
3 years ago
Lithium iodide has a lattice energy of −7.3×102kJ/mol and a heat of hydration of −793kJ/mol. Find the heat of solution for lithi
Anna007 [38]
Delta H of solution = -Lattice Energy + Hydration 
<span>Delta H of solution=- (-730)+(-793) </span>
<span>Delta H of solution= -63kJ/mol </span>

<span>Now we find moles of LiI: </span>
<span>10gLiI/133.85g=.075moles </span>
<span>multiply moles to the delta H of solution to cross cancel moles. .75moles x -64kJ/mol =4.7</span>
7 0
3 years ago
Read 2 more answers
The K w for water at 0 ∘ C is 0.12 × 10 − 14 M 2 . Calculate the pH of a neutral aqueous solution at 0 ∘ C . p H = Is a pH = 7.2
Karo-lina-s [1.5K]

Answer:

pH → 7.46

Explanation:

We begin with the autoionization of water. This equilibrium reaction is:

2H₂O  ⇄   H₃O⁺  +  OH⁻            Kw = 1×10⁻¹⁴         at 25°C

Kw = [H₃O⁺] . [OH⁻]

We do not consider [H₂O] in the expression for the constant.

[H₃O⁺] = [OH⁻] = √1×10⁻¹⁴   →  1×10⁻⁷ M

Kw depends on the temperature

0.12×10⁻¹⁴ = [H₃O⁺] . [OH⁻]  → [H₃O⁺] = [OH⁻]         at 0°C

√0.12×10⁻¹⁴ = [H₃O⁺] → 3.46×10⁻⁸ M

- log [H₃O⁺] = pH

pH = - log 3.46×10⁻⁸ → 7.46

8 0
3 years ago
Consider the following system at equilibrium at 723 K: 2 NH3 (g) 26.6 kcal N2 (g) 3 H2 (g) Indicate whether each individual chan
ZanzabumX [31]

Answer:

- To increase the temperature as it is a reactant in terms of its endothermicity.

- To remove it will enable more space for the reactant to favor its production.

- To add more reactant in order to increase its equilibrium concentration.

Explanation:

Hello,

The undergoing chemical reaction is:

2NH_3(g)\rightleftharpoons 3H_2(g)+N_2(g)

Thus, in order to intensify the amount of nitrogen as the chemical reaction is endothermic, considering the Le Chatelier's principle we state:

- To increase the temperature as it is a reactant in terms of its endothermicity.

- To remove it will enable more space for the reactant to favor its production.

- To add more reactant in order to increase its equilibrium concentration.

Best regards.

4 0
3 years ago
Determine whether each melting point observation corresponds to a pure sample of a single compound or to an impure sample with m
daser333 [38]

The question is incomplete, the complete question is;

Determine whether each melting point observation corresponds to a pure sample of a single compound or to an impure sample with multiple compounds.

Experimental melting point is BELOW literature value

Experimental melting point is CLOSE to literature value

WIDE melting point range

NARROW melting point range

Answer:

narrow melting point-pure sample of a single compound

experimental melting point is close to literature value-pure sample of a single compound

wide melting point range-impure sample of multiple compounds

experimental melting point is below literature value-impure sample of multiple compounds

Explanation:

The experimental melting point of a pure single compound is sharp and extremely close to the melting point of the substance as recorded in the literature. Usually, a pure substance melts within a narrow range of temperatures.

Impure samples of multiple compounds melt over a range of temperatures. Also if the experimental melting point is well below the record in literature, then the sample is contaminated by other compounds.

4 0
3 years ago
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