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3 years ago

Help fast! i rlly need help pls :(

Chemistry

2 answers:

mars1129 [50]3 years ago

7 0

Does it give you opinions if you click the arrow?

myrzilka [38]3 years ago

5 0

Answer:

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Explanation:

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A calorimeter contains 280.0g of water at 13.5C. When 0.250g of a substance with a molar mass of 510.0g/mol is dissolved, the te

marin [14]

The change in heat is simply equal to:

change in heat ΔH = final enthalpy – initial enthalpy

ΔH = [280.25 g * 4.18J/gC * (17.5°C)] – [280 g * 4.18J/gC * 13.5°C]

ΔH = 4,699.89 J = 4.7 kJ

Hence heat released is about 4.7 kJ

8 0

3 years ago

Ragav: is it a part of a living being? Sophie: yes it is Ragav: Is that living being an animal? Sophie: No, it's not. Ragav: doe

erma4kov [3.2K]

Answer: D. Roots

Explanation:

Sophie said that the part in question does not belong to an animal. This therefore invalidates options B and C as only animals would have lungs or legs.

Sophie then says that the part does not grow in the direction of light so that removes stems as the correct option because stems grow towards light in order to allow leaves to carry out photosynthesis.

Roots on the other hand grow towards gravity so they grow away from light which means that the correct answer is roots.

3 0

3 years ago

Which of the following hydrocarbons has a double bond in its carbon skeleton?1) C3H82) C2H63) CH44) C2H45) C2H2

Kipish [7]

Answer:

C₂H₄ (option number 4)

Explanation:

A hydrocarbon with a double bond in its carbon skeleton is an alkene and has the general form:

$C_nH_{2n}$ .

This is, the number of hydrogen atoms is twice the number of carbon atoms.

On the other hand, alkanes have only single bonds, and the compounds with a triple bond in its carbon skeleton are alkynes.

Review each choice:

1) C₃H₈:

In this case, the number of hydrogen atoms is 2×3 + 2 = 6 + 2 = 8, which is corresponds to an alkane, not an alkene.

2) C₂H₆

For this, the number of hydrogen atoms is 2 × 2 + 2 = 4 + 2 = 6. Again an alkane, not alkene.

3) CH₄

Hydrogen atoms: 1 × 2 + 2 = 4 ⇒ an alkane

4) C₂H₄

Hydrogen atoms: 2 × 2 = 4. This is precisely the relation for an alkene, so this is the hydrocarbon that has a double bond in its carbon skeleton.

The chemical formula may be writen as CH₂ = CH₂, to show the double bond.

So, this is the correct answer.

5) C₂H₂

Hydrogen atoms: 2 × 2 - 2 = 4 - 2 = 2. This relation of carbon and hydrogen atoms corresponds to a compound with triple bond, i.e an alkyne: CH≡CH.

8 0

3 years ago

Question 4 (1 point) If you have exactly one million atoms how many moles do you have?

rjkz [21]

Answer:

1.66 × 10⁻¹⁸ Moles

Explanation:

As we know one mole of any substance contains 6.022 × 10²³ particles (atoms, ions, molecules or formula units). This number is also called as Avogadro's Number.

The relation between Moles, Number of Atoms and Avogadro's Number is given as,

Number of Moles = Number of Atoms ÷ 6.022 × 10²³ Atoms/mol

Putting values,

Number of Moles = 1.0 × 10⁶ Atoms ÷ 6.022 × 10²³ Atoms/mol

Number of Moles = 1.66 × 10⁻¹⁸ Moles

7 0

3 years ago

in this trial, 0.400 M NaOH was added to 40.00 ml of 0.400 M HCl. How many ml of base must be added to cause the colour to chang

denis-greek [22]

Answer:

The amount of Ml that is needed

6 0

2 years ago