Ask question

Ask question

All categories

4 years ago

11

A 100-g piece of metal initially at T = 75C is submerged in 100 g of water initially at T = 25C. The specific heat capacity of i

ron is 0.45 J g-1 °C-1 and the specific heat capacity of water is 4.18 J g-1 °C-1. What is the final temperature of both substances in C?
a. 100
b. 75
c. 65
d. 30
e. 25

1 answer:

san4es73 [151]4 years ago

6 0

I’m not so sure but I think it’s b

You might be interested in

What mass of potassium hypochlorite (FW-90.6 g/mol) must be added to 4.50 x 10 mL of water to give a solution with pH 10.20? [Ka

marta [7]

Answer : The mass of potassium hypochlorite is, 4.1 grams.

Explanation : Given,

pH = 10.20

Volume of water = $4.50\times 10^2ml=0.45L$

The decomposition of KClO will be :

$KClO\rightarrow K^++ClO^-$

Now the further reaction with water $(H_2O)$ to give,

$ClO^-+H_2O\rightarrow HClO+OH^-$

First we have to calculate the pOH.

$pH+pOH=14\\\\pOH=14-pH\\\\pOH=14-10.20=3.8$

Now we have to calculate the $OH^-$ concentration.

$pOH=-\log [OH^-]$

$3.8=-\log [OH^-]$

$[OH^-]=1.58\times 10^{-4}M$

Now we have to calculate the base dissociation constant.

Formula used : $K_b=\frac{K_w}{K_a}$

Now put all the given values in this formula, we get :

$K_b=\frac{1.0\times 10^{-14}}{4.0\times 10^{-8}}=2.5\times 10^{-7}$

Now we have to calculate the concentration of $ClO^-$ .

The equilibrium constant expression of the reaction is:

$K_b=\frac{[OH^-][HClO]}{[ClO^-]}$

As we know that, $[OH^-]=[HClO]=1.58\times 10^{-4}M$

$2.5\times 10^{-7}=\frac{(1.58\times 10^{-4})^2}{[ClO^-]}$

$[ClO^-]=0.0999M$

Now we have to calculate the moles of $ClO^-$ .

$\text{Moles of }ClO^-=\text{Molarity of }ClO^-\times \text{Volume of solution}$

$\text{Moles of }ClO^-=0.0999mole/L\times 0.45L=0.0449mole$

As we know that, the number of moles of $ClO^-$ are equal to the number of moles of KClO.

So, the number of moles of KClO = 0.0449 mole

Now we have to calculate the mass of KClO.

$\text{Mass of }KClO=\text{Moles of }KClO\times \text{Molar mass of }KClO$

$\text{Mass of }KClO=0.0449mole\times 90.6g/mole=4.07g\approx 4.1g$

Therefore, the mass of potassium hypochlorite is, 4.1 grams.

6 0

3 years ago

A decomposition reaction has a half life of 578 years. (a) What is the rate constant for this reaction? (b) How many years does

maw [93]

Answer:

$0.001199 year^{-1}$ is the rate constant for this reaction.

It will take $1.73\times 10^3 years$ to concentration to reach 12.5% of its original value.

Explanation:

A decomposition reaction follows first order kinetics:

Half life of the reaction = $t_{1/2}=578 years$

Rate constant of the reaction = k

For first order reaction, half life and rate constant are linked with an expression :

$k=\frac{0.693}{t_{1/2}}$

$k=\frac{0.693}{578 years}=0.001199 year^{-1}$

$0.001199 year^{-1}$ is the rate constant for this reaction.

Initial concentration of reactant = $[A_o]$ = x

Final concentration of reactant after time t = $[A]$ = 12.5% of x = 0.125x

The integrated law of first order reaction :

$[A]=[A_o]\times e^{-kt}$

$0.125x=x\times e^{-0.001199 year^{-1}\times t}$

t = 1,734.31 years = $1.73\times 10^3 years$

It will take $1.73\times 10^3 years$ to concentration to reach 12.5% of its original value.

3 0

3 years ago

According to vsepr theory, a molecule with the general formula ax4e2 will have a _____ molecular shape. easynotes

Lena [83]

According to Vsepr theory, a molecule with the general formula ax4e2 will have a square planar molecular shape.The molecule of this geometry has their atoms which are positioned at the corners of the square on the same plan about a central atom.

7 0

3 years ago

Brass is stronger than steel<br> True or False

Ket [755]

False . Steel is stronger

8 0

3 years ago

Li2SO4 _____ an electrolyte in solution.<br> A. Is <br> B. Is not

Rasek [7]

Answer:

a

Explanation:

it is an electrolyte because of its strong polar chemical bond

8 0

3 years ago

Read 2 more answers