Answers
The mass of hydrogen gas obtained is 0.068 g of hydrogen gas.
The equation of the reaction is;
Ca(s) +2H2O(l) →Ca(OH)2(aq) + H2(g)
We have to obtain the number of moles of hydrogen gas produced using the information in the question.
P = 988mmHg - 17.54 mmHg = 1.28 atm
V = 641 mL or 0.641 L
T = 20 + 273 = 293 K
n = ?
R = 0.082 atmLK-1mol-1
From;
PV = nRT
n = PV/RT
n = 1.28 atm × 0.641 L/ 0.082 atmLK-1mol-1 × 293 K
n = 0.82/24.026
n = 0.034 moles
Mass of hydrogen = 0.034 moles × 2 g/mol = 0.068 g of hydrogen gas
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Answer:
There is 0.0677 grams of H2 gas obtained
Explanation:
Step 1: Data given
The total pressure (988 mmHg) is the sum of the pressure of the collected hydrogen + the vapor pressure of water (17.54 mmHg).
ptotal = p(H2)+ p(H2O)
p(H2) = ptotal - pH2O = 988 mmHg - 17.54 mmHg = 970.46 mmHg
Step 2: Calculate moles of H2 gas
Use the ideal gas law to calculate the moles of H2 gas
PV = nRT
n = PV / RT
⇒ with p = pressure of H2 in atm = 970.46 mmHg * (1 atm /760 mmHg) = 1.277 atm
⇒ V = volume of H2 in L = 641 mL x (1 L / 1000 mL) = 0.641 L
⇒ n = the number of moles of H2 = TO BE DETERMINED
⇒ R = the gas constant = 0.08206 L*atm/K*mol
⇒ T = the temperature = 20.0 °C = 293.15 Kelvin
n = (1.277)(0.641) / (0.08206)(298.15) = 0.0335 moles H2
Step 3: Calculate mass of H2
Mass of H2 = moles H2 ¨molar H2
0.0335 moles H2 * 2.02 g/mol H2 = 0.0677g H2
There is 0.0677 grams of H2 gas obtained
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B. A person who oversees the experiment to make sure it is following proper procedures.
C. The variable controlled by the scientist to affect the dependent variable.
D. The name for the set of independent and dependent variables that will be controlled by the scientist.
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Answers
The statement, that describes the ‘control’in an experiment is "the name for the set of independent and dependent variables that will be controlled by the scientist."
What is a control in experiment?
A control is an element in an experiment that remains intact or unaffected by other variables. An experiment or observation aiming to minimise the influence of variables other than the independent variable is referred to as a scientific control. It serves as a standard or point of reference against which other test findings are measured.
In a scientific experiment, an independent variable is the variable that is modified or manipulated in order to assess the effects on the dependent variable. In a scientific experiment, the dependent variable is the variable that is being tested and measured. The designation given to the set of independent and dependent variables that the scientist will regulate.
Hence the correct option is D.
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D. The name for the set of independent and dependent variables that will be controlled by the scientist.
Answers
Answer: The concentration of solution is 0.342 M
Explanation:
To calculate the molarity of solution, we use the equation:
We are given:
Mass of solute (Sodium chloride) = 15 g
Molar mass of sodium chloride = 58.5 g/mol
Volume of solution = 750 mL
Putting values in above equation, we get:
Hence, the concentration of solution is 0.342 M
Answers
Answer:
It's because the NaCl and MgCl2 is shorter and easier to remember
Answers
Given :
Mass of given magnesium chloride, m = 256 g.
To Find :
How many grams of chloride are there in 256 g of magnesium chloride.
Solution :
Molecular formula of magnesium chloride is .
Molecular formula of is, M = 95.211 g/mol .
Mass of chlorine in 1 mol of is , m = 35.5 × 2 = 71 g.
So, amount of chlorine in 256 gram :
Hence, this is the required solution.
Answers
Answer:
Four moles of electrons
Explanation:
The reactions in a breathalyzer are redox reactions. Fuel cell breathalyzers consists of fuel cells with platinum electrodes. The current produced depends on the amount of alcohol in the breath. Detection of alcohol involves the oxidation of ethanol to ethanoic acid. The two half cells set in the process are;
Anode;
C2H5OH(aq) + 4OH^-(aq) ----------> CH3COOOH(aq) + 3H2O(l) + 4e
Cathode;
O2(g) + 2H2O(l) +4e--------> 4OH^-(aq)
Hence four electrons are transferred in the process.