객관식
As the salinity of water increases, how does its density change?
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1. Intro to General Chemistry
Density
객관식
Which of the following correctly gives the mass density and the weight density of water at 4°C?
A
Mass density: 0.997 g/cm^3; Weight density: 1.00 kN/m^3
B
Mass density: 1.00 g/cm^3; Weight density: 9.81 kN/m^3
C
Mass density: 1.00 kg/m^3; Weight density: 9.81 N/m^3
D
Mass density: 9.81 g/cm^3; Weight density: 1.00 kN/m^3
검증된 단계별 안내1
Understand the definitions: Mass density (\(\rho\)) is the mass per unit volume, typically expressed in units like g/cm^3 or kg/m^3. Weight density (\(\gamma\)) is the weight per unit volume, which is the force due to gravity on the mass per unit volume, expressed in units like N/m^3 or kN/m^3.
Recall the known value for the mass density of water at 4°C, which is approximately 1.00 g/cm^3 or equivalently 1000 kg/m^3. This is a standard reference value in chemistry and physics.
Calculate the weight density using the formula:
\(\gamma = \rho \times g\)
where \(\rho\) is the mass density in kg/m^3 and \(g\) is the acceleration due to gravity (approximately 9.81 m/s^2).
Convert units carefully: Since mass density is often given in g/cm^3, convert it to kg/m^3 by multiplying by 1000 (because 1 g/cm^3 = 1000 kg/m^3). Then multiply by 9.81 m/s^2 to get weight density in N/m^3. To express weight density in kN/m^3, divide the result by 1000.
Compare the calculated values with the options given to identify the correct pair of mass density and weight density for water at 4°C.
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