Answer:
The amount of molecules → 6.02×10²³
Explanation:
Avogadro Number (NA) is the amount of particles that are contained in 1 mol of anything.
It does not matter the mass of compounds, or molecules, 1 mol has 6.02×10²³ particles, the same number for every compound.
1 mol of H₂O that weighs 18 grams has 6.02×10²³ molecules
1 mol of sucrose, that weighs 342 g has 6.02×10²³ molecules
Generally, the NA is the number of atoms in 12 grams of the carbon-12 isotope.
Answer:
The molar mass of unknown gas is 145.82 g/mol.
Explanation:
Volume of oxygen gas effused under time t = 8.24 mL
Effusion rate of oxygen gas = 
Molar mass of oxygen gas = 32 g/mol
Volume of unknown gas effused under time t = 3.86 mL
Effusion rate of unknown gas = 
Molar mass of unknown gas = M
Graham's Law states that the rate of effusion or diffusion of gas is inversely proportional to the square root of the molar mass of the gas. The equation given by this law follows the equation:




Here is the full question
Instant cold packs, often used to ice athletic injuries on the field, contain ammonium nitrate and water separated by a thin plastic divider. When the divider is broken, the ammonium nitrate dissolves according to the following endothermic reaction: NH4NO3(s)→NH+4(aq)+NO−3(aq) In order to measure the enthalpy change for this reaction, 1.25 g of NH4NO3 is dissolved in enough water to make 25.0 mL of solution. The initial temperature is 25.8 ∘C and the final temperature (after the solid dissolves) is 21.9 ∘C. Part A Calculate the change in enthalpy for the reaction in kilojoules per mole. (Use 1.0g/mL as the density of the solution and 4.18J/g⋅∘C as the specific heat capacity.) Express your answer to two significant figures and include the appropriate units. ΔHrxn = ??? kJ/mol
Answer:
26 kJ / mol
Explanation:
Given that;
The mass of NH₄NO₃ = 1.25 g
Number of moles of NH₄NO₃ = Mass of NH₄NO₃ / Molar Mass of NH₄NO₃
Number of moles of NH₄NO₃= 1.25 g / 80.043 g/mol
Number of moles of NH₄NO₃= 0.016 mol
Volume of solution = 25.0 mL
Density of Solution = 1.0g/mL
Since; 
Mass of Solution = Density x Volume
= 1.0g/mL × 25.0mL
= 25 g
Heat Generated (Q) = 
Q= 25g × 4.18 J/g°C x (25.8°C - 21.9°C)
Q = 407.55 J
Q = 407 × 10 ⁻³ kJ
Q = 0.40755 kJ
Δ
= 
= 
= 25.47 kJ/ mol
~ 26 kJ / mol
Therefore, the change in enthalpy for the reaction in kilojoules per mole = 26 kJ / mol