<span>Percentage
by mass is the amount in mass of a component in a mixture per 100 unit of
mass of the total mixture. Percentage by mass is the same as %w/w.
We can determine this by dividing the mass of the solute with the total mass of
the mixture. We calculate as follows:
Percent salt = 1.5 g salt / 30.0 g x 100 = 5% </span>
When ice melts, the physicals state changes from solid to liquid. The energy or the heat required (q) required to change a unit mass (m) of a substance from solid to liquid is known as the enthalpy or heat of fusion (ΔHf). The variables; q, m and ΔHf are related as:
q = m * ΔHf
the mass of ice m = 65 g
the heat of fusion of water at 0C = ΔHf = 334 J/g
Therefore: q = 65 g * 334 J/g = 21710 J
Now:
4.184 J = 1 cal
which implies that: 21710 J = 1 cal * 21710 J/4.184 J = 5188.8 cal
Hence the heat required is 5188.8 cal or 5.2 Kcal (approx)
Answer is: the mass of a block of magnesium is 177.75 grams.
m(Fe) = 826 g.
d(Fe) = 7.9 g/cm³.
1) Calculate volume of iron and magnesium:
d(Fe) = m(Fe) ÷ V(Fe).
V(Fe) = m(Fe) ÷ d(Fe).
V(Fe) = 826 g ÷ 7.9 g/cm³.
V(Fe) = V(Mg) = 104.56 cm³.
2) Calculate mass of magnesium:
m(Mg) = V(Mg) · d(Mg).
m(Mg) = 104.56 g/cm³ · 1.7 g/cm³.
m(Mg) = 177.75 g.
Answer:
The final volume is 39.5 L = 0.0395 m³
Explanation:
Step 1: Data given
Initial temperature = 200 °C = 473 K
Volume = 0.0250 m³ = 25 L
Pressure = 1.50 *10^6 Pa
The pressure reduce to 0.950 *10^6 Pa
The temperature stays constant at 200 °C
Step 2: Calculate the volume
P1*V1 = P2*V2
⇒with P1 = the initial pressure = 1.50 * 10^6 Pa
⇒with V1 = the initial volume = 25 L
⇒with P2 = the final pressure = 0.950 * 10^6 Pa
⇒with V2 = the final volume = TO BE DETERMINED
1.50 *10^6 Pa * 25 L = 0.950 *10^6 Pa * V2
V2 = (1.50*10^6 Pa * 25 L) / 0.950 *10^6 Pa)
V2 = 39.5 L = 0.0395 m³
The final volume is 39.5 L = 0.0395 m³
Answer:
En toda la población del mundo hay <u>0.0797 moles de células</u>
Explanation:
1.0 mol of cells = 6.022 * 10∧23 cells
X mol of cells = 6.0 * 10∧12 cells
- X is cleared to find out how many moles of cells are in a human body:
- X = 6.0 * 10∧12 cells / 6.022 * 10∧23 cells
- X = 9,963 * 10∧-12 moles of cells per person
In the world there are 8 * 10∧9 people, how many moles in total will there be?
8 * 10∧9 people * 9,963 * 10∧-12 moles of cells per person =
<u>0.0797 moles of molecules in the entire population of the earth.</u>
