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3 years ago

I have a exam please answer fast

Chemistry

1 answer:

VLD [36.1K]3 years ago

3 0

Answer:

$\triangle \: H {}^{ \theta} _{s} = lattice \: energy + hydration \: energy \\ = + 2526 + ( - 2003 + (2 \times - 340)) \\ + 2526 - 2683 \\ = - 157 \: kjmol {}^{ - 1}$

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A megamole of titanium contains __________ moles of titanium.

Gala2k [10]

Answer is: 1 megamole is equal to 1000000 (one million) mole or 10⁶ moles.
The SI base unit for amount of substance is the mole. The SI prefix "mega" represents a factor of 10⁶, or in exponential notation, 1E6.
The mole is the amount of substance of a system which contains as many elementary entities as there are atoms in 12 grams of carbon C-12.

8 0

3 years ago

Read 2 more answers

5. A 25 kg object travels a distance of 90 m in 30 s. Find the momentum

xz_007 [3.2K]

Answer:

★ v = d/t

★ v = 90/30

★ v =3

Acc to question

★ momentum = mass * velocity

★ m = 25×3

★ m = 75kgm/s

Hope it help

6 0

3 years ago

Read 2 more answers

In the laboratory a student uses a "coffee cup" calorimeter to determine the specific heat of a metal. She heats 19.6 grams of z

storchak [24]

Answer:

The specific heat of zinc is 0.375 J/g°C

Explanation:

Step 1: Data given

Mass of zinc = 19.6 grams

Mass of water = 82.9 grams

Initial temperature of zinc T1= 98.37 °C

Initial temperature of water T1= 24.16 °C

Final temperature of water (and zinc) T2 = 25.70 °C

Specific heat of water = 4.184 J/g°C

Step 2: Calculate Specific heat of zinc

Q=m*c*ΔT

Qzinc = -Qwater

m(zinc)*C(zinc)*ΔT(zinc) = -m(water)*C(water)*ΔT(water)

⇒ with mass of water = 82.9 grams

⇒ with C(water) = 4.184 J/g°C

⇒ with ΔT(water) = T2 - T1 = 25.70 - 24.16 = 1.54

⇒ with mass of zinc = 19.6 grams

⇒ with C(zinc) = TO BE DETERMINED

⇒ with ΔT(zinc) = T2 -T1 = 25.70 - 98.37 = -72.67°C

Qzinc = -Qwater

m(zinc)*c(zinc)* ΔT(zinc) = - m(water)*c(water)* ΔT(water)

19.6g* C(zinc) * (-72.67°C) = - 82.9g* 4.184 J/g°C * 1.54 °C

-1424.332*C(zinc) = -534.155

C(zinc) = 0.375 J/g°C

The specific heat of zinc is 0.375 J/g°C

4 0

3 years ago

(b) Use the first law of thermodynamic to calculate AU for the following situations: (i) A coiled spring unwinds producing 153 J

il63 [147K]

Answer:

(i) ΔU = 116 J

(ii) ΔU = 289 J

(iii) ΔU = 1 KJ

(iv) ΔU = 0 J

(v) ΔU = 3.25 KJ

Explanation:

first law:

ΔU = Q + W

(i) W = 153 J; Q = - 37 J ( Q ( - ), losing friction )

⇒ ΔU = 153 - 37 = 116 J

(ii) W = 289 J; Q = 0 ( insulated)

⇒ ΔU = W = 289 J

(iii) Q = 1 KJ , W = 0 ( isovolumetric process)

⇒ ΔU = Q = 1 KJ

(iv) isothermal ( constant temperature )

ΔU = Cv * ΔT

∴ ΔT = 0° ( isothermal )

⇒ ΔU = 0 J

(v) isobaric ( constant pressure )

⇒ ΔU = Q + W

∴ Q = 15.6 KJ

∴ W = - ∫ P dV = - P ΔV; W (-) the system performs a job and the volume increases

∴ P = 950 KPa * ( 1000 Pa / KPa ) = 950000 Pa = 950000 J/m³

∴ ΔV = 18 - 5 = 13 L * ( m³ / 1000 L ) = 0.013 m³

⇒ W = - ( 950000 J/m³) * ( 0.013 m³ ) = - 12350 J ( - 12.35 KJ )

⇒ ΔU = 15.6 KJ + ( - 12.35 KJ )

⇒ ΔU = 3.25 KJ

7 0

3 years ago

Sodium borodeuteride is a commercially available reducing reagent that can convert aldehydes and ketones to the corresponding al

kupik [55]

Here we have to draw the mechanism of the reduction reaction between benzaldehyde and sodium borodeuteride to form the corresponding alcohol.

The reducing agent sodium borodeuteride can reduce the aldehydes to its corresponding alcohol. The reaction mechanism is shown in the attached image.

The reaction mechanism can be explained as-

The sodium borodeuteride is highly ionic in nature thus it remains as Na⁺ and BD₄⁻ The deuterium atom of BD₄⁻ attack the carbonyl carbon atom and substitute one of its deuterium as shown in the figure.

One molecule of sodium borodeuteride can reduce four molecules of benzaldehyde. The polar solvent like alcohol donates the proton as shown in the mechanism.

The converted alcohol contains the deuterium atom at the -C center. Thus benzaldehyde is converted to deuteroted benzyl alcohol.

3 0

3 years ago