Half-life is defined as the amount of time it takes a given quantity to decrease to half of its initial value. The equation to describe the decay is
Nt=N0(1/2)
where N0 is the initial quantity, Nt is the remaining quantity after time t, t1/2 is the half-time. So work out the equation, t1/2 = t (-ln2)/ln(Nt/N0) = 11.5*(-ln2)/ln(12.5/100) = 3.83 days
Answer;
-The above statement is true.
During a medical screening, lung capacity testing is a standard procedure
Explanation;
-Lung capacity testing also the pulmonary function test is a part of medical screening that is done to diagnose certain types of lung disease, such as asthma, bronchitis, and emphysema. Find the cause of shortness of breath and also measure whether exposure to chemicals at work affects lung function.
Answer:
CH₂ ; 67.1 %
Explanation:
To determine the empirical formula we need to find what the mole ratio is in whole numbers of the atoms in the compound. To do that we will first need the atomic weights of C and H and then perform our calculation
Assume 100 grams of the compound.
# mol C = 85.7 g / 12.01 g/mol = 7.14 mol
# mol H = 14.3 g / 1.008 g/mol = 14.19 mol
The proportion is 14.9 mol H/ 7.14 mol C = 2 mol H/ 1 mol C
So the empirical formula is CH₂
For the second part we will need to first calculate the theoretical yield for the 12.03 g NaBH₄ reacted and then calculate the percent yield given the 0.295 g B₂H₆ produced.
We need to calculate the moles of NaBH₄ ( M.W = 37.83 g/mol )
1.203 g NaBH₄ / 37.83 g/mol = 0.0318 mol
Theoretical yield from balanced chemical equation:
0.0318 mol NaBH₄ x 1 mol B₂H₆ / mol NaBH₄ = 0.0159 mol B₂H₆
Theoretical mass yield B₂H₆ = 0.0159 mol x 27.66 g/ mol = 0.440 g
% yield = 0.295 g/ 0.440 g x 100 = 67.1 %
Answer:
[H₂SO₄] = 6.07 M
Explanation:
Analyse the data given
8.01 m → 8.01 moles of solute in 1kg of solvent.
1.354 g/mL → Solution density
We convert the moles of solute to mass → 8.01 mol . 98g /1mol = 785.4 g
Mass of solvent = 1kg = 1000 g
Mass of solution = 1000g + 785.4 g = 1785.4 g
We apply density to determine the volume of solution
Density = Mass / volume → Volume = mass / density
1785.4 g / 1.354 g/mL = 1318.6 mL
We need this volume in L, in order to reach molarity:
1318.6 mL . 1L / 1000mL = 1.3186 L ≅ 1.32L
Molarity (mol/L) → 8.01 mol / 1.32L = 6.07M