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2 years ago

Describe how to properly measure the volume of a liquid.

Chemistry

2 answers:

marusya05 [52]2 years ago

5 0

The best way to measure it usually is to use a beaker or graduated cylinder.

Sergeu [11.5K]2 years ago

5 0

Use a graduated cylinder.

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A resistor has a voltage Across it of 3kv and a current through it of 3m A .

Oliga [24]

The correct answer is B

6 0

2 years ago

The exhaust gas from an automobile contains 1.5 percent by volume of carbon monoxide. What is the concentration of CO in mg/m' a

FrozenT [24]

Answer:

(a) 17,178 mg/m3

(b) 11,625 mg/m3

Explanation:

The concentration of CO in mg/m3 can be calculated as

$C (mg/m3) =(P/RT)*MW*C_{ppm}$

For standard conditions (1 atm and 25°C), P/RT is 0.0409.

Concentration of 1.5% percent by volume of CO is equivalent to 1.5*10,000 ppm= 15,000 ppm CO.

The molecular weigth of CO is 28 g/mol.

(1) For 25°C and 1 atm conditions

$C=(P/RT)*MW*C_{ppm}\\\\C=0.0409*28*15,000=17,178$

(b) For 200°C and 1.1 atm,

$P/RT=0.0409*(P/P_{std})*(T_{std}/T)\\P/RT=0.0409*(1.1atm/1atm)*(273+15K/273+200K)=0.0277$

Then the concentration in mg/m3 is

$C=(P/RT)*MW*C_{ppm}\\\\C=0.0277*28*15,000=11,625$

5 0

2 years ago

Using standard heats of formation, calculate the standard enthalpy change for the following reaction. 2NH3(g) 3N2O(g)4N2(g) 3H2O

trasher [3.6K]

Answer: $\Delta H^{0} = -879.15 kJ/mol$

Explanation: Heats of formation is the amount of heat necessary to create 1 mol of a compound from its molecular constituents. The basic conditions the substance is formed is at standard conditions: 1 atm and 25°C. Each compound has its own heat of formation per mol of compound (kJ/mol), but to an element is assigned a value of zero.

Standard Enthalpy Change is defined as the heat absorbed or released when a reaction takes place. It can be positive or negative, which means reaction is endothermic or exothermic, respectively.

Enthalpy change is calculated as the difference between the sum of heat formation of products and the sum of heat formation of the reactants:

$\Delta H^{0}=\Sigma H^{0}_{f}_{(products)}-\Sigma H^{0}_{f}_{(reactants)}$

For the reaction

2NH₃ + 3N₂O → 4N₂ + 3H₂O

2(-46.2) + 3(82.05) 4(0) + 3(-241.8)

$\Delta H^{0}=3(-241.8)-[ 2(-46.2)+3(82.05)]$

$\Delta H^{0}=-725.4-153.75$

$\Delta H^{0}=-879.15$

The standard enthalpy change for the reaction is $\Delta H^{0}=-879.15$ kJ

8 0

2 years ago

Lab: Limiting Reactant and Percent Yield

creativ13 [48]

Answer : If a substance is the limiting reactant, then it limits the formation of products because in the reaction it is present in limited amount.

Explanation :

While observing a chemical reaction, we can tell about whether a reactant is limiting or excess.

Step 1 : first write the chemical reaction and then balanced the chemical equation.

$C_2H_4+H_2\rightarrow C_2H_6$

Step 2 : convert the given masses into the moles if mass of $C_2H_4$ is 10.5 g and molar mass of $C_2H_4$ is 28 g/mole and the mass of hydrogen is 0.40 g and molar mass of hydrogen is 2 g/mole.

$\text{moles of }C_{2}H_{4}=\frac{10.5g}{28g/mole}=0.375moles$

$\text{moles of }H_{2}=\frac{0.40g}{2g/mole}=0.20moles$

Step 3 : Now we have to determine the limiting reagent and excess reagent.

$\text{ moles of }C_{2}H_{4}\text{ in excess}=0.375-0.20=0.175\text{moles}$

Now we conclude that $C_{2}H_{4}$ is the limiting reagent and hydrogen is an excess reagent.

Hypothesis :

Limiting reagent : It is the reagent in the chemical reaction that is totally consumed when the chemical reaction is complete. Limiting reagent limits the formation of products.

7 0

2 years ago

Read 2 more answers

A sample is decomposed in the laboratory and found that it contains 52.2% carbon (C), 13.0% hydrogen (H), and 34.8% oxygen (O).

Andrej [43]

The empirical formula would be C2H6O

7 0

3 years ago