[need answers with steps right away! ]
2.0g of ch4 (16.0) are added to 3.0g of o2 (32.0) at 400k and 950torr. what volume does this mixture occupy?

a 300 ml sample of gas was collected at stp weighs .90g. what is the molar mass of this gas?

1) 5.74 L.

2) 67.158 g/mol.

Explanation:

Q1:

PV = nRT

P is the pressure of the gases (P = 950 torr / 760 = 1.25 atm).

V is the volume of the gases (V = ??? L).

R is the general gas constant (R = 0.082 L.atm/mol.K).

T is the temperature of the gases (T = 400 K).

n is the no. of moles of the gases.

no. of moles of CH₄ = mass / molar mass = (2.0 g) / (16.0 g/mol) = 0.125 mol.

no. of moles of O₂ = mass / molar mass = (3.0 g) / (32.0 g/mol) = 0.09375 mol.

∴ n = no. of moles of CH₄ + no. of moles of O₂ = 0.125 mol + 0.09375 mol =  0.21875 mol.

∴ V = nRT/P = (0.21875 mol)(0.082 L.atm/mol.K)(400 K) / (1.25 atm) = 5.74 L.

Q2:

PV = (mass/molar mass)RT.

The molar mass = (mass)RT/PV.

The mass of the gas = 0.90 g.

R = 0.082 L.atm/mol.K.

T = 273 K at STP conditions.

P = 1.0 atm at STP conditions.

V = 300.0 mL = 0.30 L.

yes

ya te ayud espera

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.