Answer:
-41. 47
Explanation:
m = q / Cp x T
m = Mass
q = Energy (or joules)
Cp = Heat Capacity
T = Change in Temperature
Water's heat capacity is always 4.18.
This is the formula you'll need for change in temperature:
Final - Initial
So, 33 - 78 = -45
m = 7800 / 4.18 x -45
= -41.47
When ice forms, the molecules are farther apart than in liquid water, allowing the ice to form an organized crystal structure and float.
Answer:
Formular = C₅H₁₁NO₃
Explanation:
The empirical formular is the simplest formular of a compound can have.
We use the steps below to obtain the empirical formular;
Step 1: Obtain the mass of each element present in grams. Element % = mass in g = m.
Carbon = 45.46% = 45.46g
Hydrogen = 7.63% = 7.63g
Nitrogen = 10% = 10g
Oxygen = 100% - (45.46% + 7.63% + 10%) = 36.31% = 36.31g
Step 2: Determine the number of moles of each type of atom present.
Molar amount (M) = m/atomic mass
Carbon = 45.46 / 12 = 3.7883
Hydrogen = 7.63 / 1 = 7.63
Nitrogen = 10 / 14 = 0.7143
Oxygen = 36.91 / 16 = 2.3069
Step 3: Divide the number of moles of each element by the smallest number of moles. Smallest = 0.7143
Carbon = 3.7883 / 0.7143 = 5.3035
Hydrogen = 7.63 / 0.7143 = 10.67
Nitrogen = 0.7143 / 0.7143 = 1
Oxygen = 2.2693 / 0.7143 = 3.1770
Step 4: Convert numbers to whole numbers
Carbon = 5
Hydrogen = 11
Nitrogen = 1
Oxygen = 3
Formular = C₅H₁₁NO₃
Answer:
Density, melting point. and magnetic properties
Explanation:
I can think of three ways.
1. Density
The density of Cu₂S is 5.6 g/cm³; that of CuS is 4.76 g/cm³.
It should be possible to distinguish these even with high school equipment.
2. Melting point
Cu₂S melts at 1130 °C (yellowish-red); CuS decomposes at 500 °C (faint red).
A Bunsen burner can easily reach these temperatures.
3. Magnetic properties
You can use a Gouy balance to measure the magnetic susceptibilities.
In Cu₂S the Cu⁺ ion has a d¹⁰ electron configuration, so all the electrons are paired and the solid is diamagnetic.
In CuS the Cu²⁺ ion has a d⁹ electron configuration, so all there is an unpaired electron and the solid is paramagnetic.
A sample of Cu₂S will be repelled by the magnetic field and show a decrease in weight.
A sample of CuS will be attracted by the magnetic field and show an increase in weight.
In the picture below, you can see the sample partially suspended between the poles of an electromagnet.
