Chemistry, 27.09.2019 17:30 Annaborden02

Ablock of copper of unknown mass has an initial temperature of 65.4 ∘c. the copper is immersed in a beaker containing 95.7 g of water at 22.7 ∘c. when the two substances reach thermal equilibrium, the final temperature is 24.2 ∘c. what is the mass of the copper block? express your answer in grams to three significant figures.

Answers

Answer from: ayoismeisalex

The mass of the copper block in grams is calculated to be 37.9g

HOW TO CALCULATE MASS IN COLORIMETRY.

The mass of a substance in colorimetry can be calculated by using the formula below:

Q = m × c × ∆T

Where;

Q = amount of heat absorbed or released (J)m = mass of substance (g)c = specific capacity of substance (J/g°C)∆T = change in temperature (°C)

In this case;

Q(water) = -Q(copper)

m.c.∆T (water) = -m.c∆T (copper)

As given in this question;

FOR WATER:

m = 95.7gc = 4.184 J/g°C∆T = 24.2°C - 22.7°C = 1.5°C

FOR COPPER:

m = ?c = 0.385 J/g°C∆T = 24.2°C - 65.4°C = -41.2°C

m.c.∆T (water) = -m.c∆T (copper)

95.7 × 4.184 × 1.5 = - (m × 0.385 × -41.2)

600.6132 = -(-15.862m)

600.6132 = 15.862m

m = 600.6132 ÷ 15.862

m = 37.9g

Therefore, the mass of the copper block in grams is calculated to be 37.9g.

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Answer from: dasharia

The mass of the copper block: 37,829 g

Further explanation

The law of conservation of energy can be applied to heat changes, i.e. the heat received / absorbed is the same as the heat released

Q in = Q out

Heat can be calculated using the formula:

$\rm \large{\boxed{\bold{Q=m\times c\times \Delta T}}}$

Q = heat, J

m = mass, g

c = specific heat, joules / g ° C

∆T = temperature difference, ° C / K

1. H₂O

m = 95.7 g

c = 4.18 J / gºC

delta T = 24.2 °C - 22.7 °C = 1.5 °C

Q H₂O = 95.7 x 4.18 x 1.5

Q H₂O = 600,039 J

2. Cu

c = 0.385 J / gºC

delta T = 65.4 °C - 24.2 °C = 41.2 °C

QH₂O = Q Cu

600,039 J = m. 0.385 J / gºC. 41.2. °C

$\rm m=\dfrac{600.039}{0.385\times 41.2}\\\\m=\boxed{37.829\:g}}$

Learn more

the difference between temperature and heat

link

Specific heat

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relationships among temperature, heat, and thermal energy.

link

When heat is added to a substance

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Answer from: Quest

1.consider the following balanced equation and answer parts a through. show calculations for each part.

3 ag(s) + 4 hno3(aq) → 3 agno3(aq) + no(g) + 2 h2o(l)

a. calculate the number of moles of agno3 produced by the reaction of 3 moles of ag with excess hno3. if the number to the left of the compound represents the number of moles of the compound which are present, then 3 moles of ag react with 4 moles hno3 to produce 3 moles agno3 (aq).

so the answer to a would be 3 moles.

b. calculate the number of moles of agno3 produced by the reaction of 108 grams of ag with excess hno3.

i'm not sure how to plug in the grams of silver into an equation using moles to find how many moles are produced.

c. calculate the number of grams of agno3 produced by the reaction of 108 grams of ag with excess hno3

d. calculate the number of moles of no produced as a byproduct of the reaction of 108 grams of ag with excess hno3.

e. calculate the number of grams of no produced as a byproduct starting with 108 grams of ag and excess hno3.

explanation:

Answer from: Quest

a saline water is fed to a reverse osmosis unit at flow rate o rotameter connected to reject (retentate) line reads 8 installed in reject and permeate line reads 15.2 milli siemens/cm and 300 micro siemens/com respectively.

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Ablock of copper of unknown mass has an initial temperature of 65.4 ∘c. the copper is immersed in a...