Answer:
The ΔH of the reaction is + 12.45 KJ/mol
Explanation:
Mass of water= 100ml = 100g. (You should always assume 1cm3 of water as 1g)
heat capacity of water = 4.18 Jk-1 Mol-1
Change in temperature = (19.86 - 25.00) = -5.14 K (This is an endothermic reaction because of the fall in temperature)
Molar mass of NaHCO3 = 84 g/mol
Mole of NaHCO3 = 14.5 / 84 = 0.173 mol
Step 1 : Calculate the heat energy (Q) lost by the water.
Q = M x C x ΔT
Q = -100 x 4.18 x (-5.14)
Q = 2148.5 joules
Q = 2.1485 K J
Step 2: Calculating the ΔH of the reaction?
ΔH = Q / number of moles of NaHCO3
ΔH = 2.1485 / 0.173
ΔH = 12.42 KJ/mol
<h2>Relative Humidity</h2>
Explanation:
- Humidity is the amount of moisture content present in the atmosphere.
Humidity is of two types:
- Absolute humidity.
- Relative humidity.
- Absolute humidity is the ratio of the amount of moisture content in the air to the unit volume of the air.
- Relative humidity can be derived as the ratio of moisture content in the air to the maximum amount of moisture that the air constitutes.
- Hence, the required answer is Relative humidity.
Answer:
option C= patterns
Explanation:
The periodic table is helpful to identify the element readily. All the elements are arranged properly. The elements with same physical and chemical properties are placed in same group and period. Periodic table is also helpful to predict the properties of those elements which are not discovered yet. This table is also very helpful to balance the chemical equations. The horizontal rows are called periods while vertical column are called groups. There are seven periods and eighteen groups are in periodic table.
Trends in periodic table:
As we move left to right in a period the atomic radius is decreases with increase of atomic number. The ionization energy goes to increases from left to right in period because of greater hold of nuclear charge on valance electron, so that's way more energy is required to overcome this charge and to make the atom ionic.
From left to right in period electron affinity and electronegativity also increases.
As we move top to bottom in group ionization energy decreases with increase of atomic number because of large atomic radius. The valance electron require less energy to move free. The electron affinity and electronegativity also decreases from top to bottom.
According the VSEPR theory the molecular geometry for CH3+ is triagonal planar
This question is missing the part that actually asks the question. The questions that are asked are as follows:
(a) How much of a 1.00 mg sample of americium remains after 4 day? Express your answer using 2 significant figures.
(b) How much of a 1.00 mg sample of iodine remains after 4 days? Express your answer using 3 significant figures.
We can use the equation for a first order rate law to find the amount of material remaining after 4 days:
[A] = [A]₀e^(-kt)
[A]₀ = initial amount
k = rate constant
t = time
[A] = amount of material at time, t.
(a) For americium we begin with 1.00 mg of sample and must convert time to units of years, as our rate constant, k, is in units of yr⁻¹.
4 days x 1 year/365 days = 0.0110
A = (1.00)e^((-1.6x10^-3)(0.0110))
A = 1.0 mg
The decay of americium is so slow that no noticeable change occurs over 4 days.
(b) We can simply plug in the information of iodine-125 and solve for A:
A = (1.00)e^(-0.011 x 4)
A = 0.957 mg
Iodine-125 decays at a much faster rate than americium and after 4 days there will be a significant loss of mass.
