What total mass of a 16 gram sample of 60Co will remain unchanged after 15.9 years

The heat of combustion of wood is approximately 16 kJ/g. What is the final temperature that 500.0 mL of water, initially at 25.0

marissa [1.9K]

Answer:

The final temperature is 34,2 ºC when 1,20 g of wood is burned inside the calorimeter.

Explanation:

The heat of combustion of wood which is approximately 16 kJ/g means that 1 g requires 16 kJ of heat so let's calculate about 1,20 g which is the value of wood you have.

1 g ________ 16 kJ

1,20 g ______ 1,20 g x 16 kJ = 19,2 kJ = 19200 J

Now let's apply the calorimetry formula

Q = m . C . ΔT

19200 J = 500 g . 4,186 J/ gºC ( Tfinal - 25ºC)

<em>Look that we don't have the mass of water, instead we have the volume so as you know water density is 1 g/ml, we conclude that in 500 ml, we have 500 g.</em>

On the other hand we convert the 19.2 kJ into J (* 1000) by the units in the value of the specific heat of the water, it is in Joule

19200 J = 500 g . 4,186 J/ gºC ( Tfinal - 25ºC)

19200 J = 2093 J/ºC ( Tfinal - 25ºC)

19200 J = 2093 J/ºC .Tfinal - 52,325 J

19200 J + 52325 J = 2, 093 J/ºC .Tfinal

71525 J = 2093 J/ºC .Tfinal

71525 J /2093 ºC / J = Tfinal = 34,17ºC

8 0

3 years ago

What is the pH of a solution obtained by dissolving two extra-strength aspirin tablets, containing 470 mg of acetylsalicylic aci

Advocard [28]

Answer:

2.58

Explanation:

Each tablet has a mass of 470 mg. The mass of 2 tablets is 2 × 470 mg = 940 mg = 0.940 g

The molarity of acetylsalicylic acid (aa) is:

M = mass of aa / molar mass of aa × liters of solution

M = 0.940 g / 180.16 g/mol × 0.240 L

M = 0.0217 M

Acetylsalicylic acid is a weak acid, so we can find [H⁺] using the following expression.

[H⁺] = √(Ca × Ka)

where,

Ca: concentration of the acid

Ka: acid dissociation constant

[H⁺] = √(0.0217 × 3.24 × 10⁻⁴)

[H⁺] = 2.65 × 10⁻³ M

The pH is:

pH = -log [H⁺] = -log 2.65 × 10⁻³ = 2.58

6 0

3 years ago

What mass of ni has as many atoms as there are n atoms in 63.0 g of no2?

adoni [48]

Answer : The mass of Ni is, 80.346 g

Solution :

First we have to calculate the number of moles.

$\text{Moles of }NO_2=\frac{\text{Mass of }NO_2}{\text{Molar mass of }NO_2}=\frac{63g}{46g/mole}=1.369moles$

Now we have to calculate the number of atoms of $NO_2$

As 1 moles $NO_2$ contains $6.022\times 10^{23}$ number of molecules

So, 1.369 moles $NO_2$ contains $1.369\times 6.022\times 10^{23}$ number of molecules

One $NO_2$ molecule has one nitrogen atom then $1.369\times 6.022\times 10^{23}$ number of molecules of $NO_2$ will contain $1.369\times 6.022\times 10^{23}$ number of nitrogen atoms

As per question number of Ni atoms is equal to the number of nitrogen atoms

Number of Ni atoms= $1.369\times 6.022\times 10^{23}$ atoms

Number of moles = $\frac{1.369\times 6.022\times 10^{23}}{6.022\times 10^{23}}=1.369moles$

Mass of Nickel = $Moles\times \text{Molecular mass}}$

Molecular mass of Nickel = 58.69 g/mol

Mass of nickel = $1.369mol\times 58.69g/mol=80.346grams$

8 0

3 years ago

Read 2 more answers

When you turn on a radio, what type of energy transformation takes place?

Nonamiya [84]

Answer:

Its D

Explanation:

8 0

3 years ago

How many grams nano3 add to 500g of h20 prepare solution .5 molal nano3?

Scilla [17]

Answer is: mass of sodium nitrate is 21,25 g.
m(H₂O) = 500 g · 1 kg/1000 g = 0,5 kg.
b(solution) = 0,500 m = 0,500 mol/kg.
m(NaNO₃) = ?
b(solution) = n(NaNO₃) ÷ m(H₂O).
n(NaNO₃) = 0,500 mol/kg · 0,5 kg.
n(NaNO₃) = 0,25 mol.
m(NaNO₃) = n(NaNO₃) · M(NaNO₃).
m(NaNO₃) = 0,25 mol · 85 g/mol.
m(NaNO₃) = 21,25 g.

8 0

3 years ago