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alexandr402 [8]

2 years ago

14

When one form of energy is converted to another form in any physical or chemical change, energy input alwasy equals energy outpu

t?

1 answer:

aliya0001 [1]2 years ago

5 0

In the context of chemistry, yes. Energy input is always equal to the energy output.

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What are the two most abundant elements in the universe

Yuri [45]

The two most abundant elements in the universe are HYDROGEN AND HELIUM. Hydrogen is the most abundant element followed by helium.
Hydrogen is the lightest of all element and the first element to be formed, followed by helium which has just two atoms.

4 0

3 years ago

Read 2 more answers

Joan’s initial nickel (II) chloride sample was green and weighed 4.3872 g. After the dehydration reaction and removal of excess

ANEK [815]

Answer:

a) yes, it was an hydrate

b) the number of waters of hydration, x = 6

Explanation:

a) yes it was an hydrate because the mass decreased after the process of dehydration which means removal of water thus some water molecules were present in the sample.

b) NiCl2. xH2O

mass if dehydrated NiCl2 = 2.3921 grams

mass of water in the hydrated sample = mass of hydrated - mass of dehydrated = 4.3872 - 2.3921 = 1.9951 g which represent the mass of water that was present in the hydrated sample.

NiCl2.xH2O

mole of dehydrated NiCl2 = m/Mm = 2.3921/129.5994 = 0.01846 mole

mole of water = m/Mm = 1.9951/18.02 = 0.11072 mole

Divide both by the smallest number of mole (which is for NiCl2) to find the coefficient of each

for NiCl2 = 0.01846/0.01846 = 1

for H2O = 0.11072/0.01846 = 5.9976 = 6

thus the hydrated sample was NiCl2. 6H2O

4 0

3 years ago

1. Given below are the figures showing particles of a matter in its three

stepan [7]

Answer:the answer is c

Explanation:

6 0

3 years ago

0.53g of acetanilide was subjected to kjeldahl determination and the ammonia produced was collected in 50cm3 of 0.50M of h2so4.o

Lady bird [3.3K]

Answer:

10.57% of N in acetanilide

Explanation:

All nitrogen in the sample is converted in NH₃ in the Kjeldahl determination. The NH₃ reacts with H₂SO₄ as follows:

2NH₃ + H₂SO₄ → 2NH₄⁺ + SO₄²⁻

The acid in excess in titrated with Na₂CO₃ as follows:

Na₂CO₃ + H₂SO₄ → Na₂SO₄ + H₂O + CO₂

To solve this question we must find the moles of sodium carbonate = Moles of H₂SO₄ in excess. The added moles - Moles in excess = Moles of sulfuric acid that reacts:

<em>Moles Na₂CO₃ anf Moles H₂SO₄ in excess:</em>

0.025L * (0.05mol / L) = 1.25x10⁻³ moles Na₂CO₃ / 0.01360L =

0.09191M * 0.250L = 0.0230 moles H₂SO₄ in excess.

<em>Moles H₂SO₄ added:</em>

0.050L * (0.50mol / L) = 0.0250 moles H₂SO₄ added

<em>Moles that react:</em>

0.0250 moles - 0.0230 moles = 0.0020 moles H₂SO₄

<em>Moles of NH₃ = Moles N:</em>

0.0020 moles H₂SO₄ * (2mol NH₃ / 1mol H₂SO₄) = 0.0040 moles NH₃ = Moles N

<em>mass N and mass percent:</em>

0.0040 moles N * (14g / mol) = 0.056gN / 0.53g * 100 =

<h3>10.57% of N in acetanilide</h3>

7 0

2 years ago

PLEASE HELP ASAP!!!!

Sonja [21]

<span>c. About one month To answer this question, TAKE A LOOK AT THE GRAPH. If you do so, you'll see that the first peak for prey happens at about 2.5 months. The first peak for predators happens at about 3.5 months, or in other words, lags by about a month. Looking at the second peak for prey and predator you see the figures of 8 months and 9 months. Another lag of about 1 month. Looking at the third peak, you see a bit past 13 months and a bit past 14 months. Another one month lag. Therefore the answer is "c. About one month"</span>

8 0

3 years ago