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Varvara68 [4.7K]

3 years ago

15

A mechanic repaired 28 cars and 46 trucks last month. He spent 2.5 hours repairing each of these vehicles. Which equation can be

used to find h, the total number of hours the mechanic spent repairing these vehicles?

1 answer:

Simora [160]3 years ago

8 0

28+46 =74(total number of vehicles)
74 x 2.5 = h(Total number of vehicles x hours spent per vehicle)

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What's metamorphism?

nata0808 [166]

Answer:

d

Explanation:

4 0

3 years ago

Read 2 more answers

The activation energy of an uncatalyzed reaction is 70 kJ/mol. When a catalyst is added, the activation energy (at 20 °C) is 42

denis23 [38]

Answer:

T = 215.33 °C

Explanation:

The activation energy is given by the Arrhenius equation:

$k = Ae^{\frac{-Ea}{RT}}$

<u>Where:</u>

k: is the rate constant

A: is the frequency factor

Ea: is the activation energy

R: is the gas constant = 8.314 J/(K*mol)

T: is the temperature

We have for the uncatalyzed reaction:

Ea₁ = 70 kJ/mol

And for the catalyzed reaction:

Ea₂ = 42 kJ/mol

T₂ = 20 °C = 293 K

The frequency factor A is constant and the initial concentrations are the same.

Since the rate of the uncatalyzed reaction (k₁) is equal to the rate of the catalyzed reaction (k₂), we have:

$k_{1} = k_{2}$

$Ae^{\frac{-Ea_{1}}{RT_{1}}} = Ae^{\frac{-Ea_{2}}{RT_{2}}}$ (1)

By solving equation (1) for T₁ we have:

$T_{1} = \frac{T_{2}*Ea_{1}}{Ea_{2}} = \frac{293 K*70 kJ/mol}{42 kJ/mol} = 488. 33 K = 215.33 ^\circ C$

Therefore, we need to heat the solution at 215.33 °C so that the rate of the uncatalyzed reaction is equal to the rate of the catalyzed reaction.

I hope it helps you!

4 0

4 years ago

Given the equation 2mg(s) + o2(g) → 2mgo(s) + 72.3 kj, how much heat is involved in the production of 5.0 mol of mgo? question 2

Rudik [331]

The heat is involved in the production of 5.0 mol of MgO is 180 Kj

   calculation

2 Mg (s) +O2 → 2 MgO

From the equation above two moles of MgO is used therefore

72.3 is for 2 moles

that is 72.3 kj = 2moles
? = 5 moles

by cross multiplication

= 72.3 kj × 5/2 = 180 Kj

7 0

3 years ago

How many moles is 1.25 x 1024 atoms of bromine?

Irina-Kira [14]

Answer:

2.08 moles (3 s.f.)

Explanation:

number of moles

= number of atoms ÷ Avogadro's constant

Avogadro's constant= 6.022 ×10²³

Thus, number of moles

= 1.25×10²⁴ ÷ (6.022 ×10²³)

= 2.08 moles (3 s.f.)

8 0

3 years ago

3. The complex ion Co(H2O)6 2(aq) is pink when placed in solution. Addition of chloride ions creates an equilibrium with CoCl42-

mart [117]

Answer:

See explanation

Explanation:

When the complex ion Co(H2O)6 2+(aq) is placed in solution and chloride ions are added, the following equilobrium is set up;

Co(H2O)62+(aq) + 4 Cl-(aq) <=> CoCl42-(aq) + 6 H2O(g)

Co(H2O)6 2+(aq) solution is pink in colour while CoCl42-(aq) solution is blue in colour.

Since the solubility of CoCl42-(aq) is endothermic, heating the solution will move the equilibrium position towards the right (more CoCl42-(aq) is formed and the solution is blue in colour).

When the solution is cooled, more Co(H2O)62+(aq) is formed and the equilibrium position shifts towards the left and the solution becomes pink in colour.

6 0

3 years ago