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The statement “the scientific process is open ended” means:

mina [271]

Answer:

think it helps you

<h2>Explanation:</h2>

<em><u>The statement “the scientific process is open ended” means: Would an element with 7 valence electrons be more or less reactive than an element with 3 valence electrons? Element 1 is a hard dark-red solid</u></em>

4 0

3 years ago

Refrigerant-134a enters the coils of the evaporator of a refrigeration system as a saturated liquid-vapor mixture at a pressure

Firdavs [7]

Answer:

(a) 0.699 kJ/K

(b) -0.671 kJ/K

(c) 0.028 kJ/K

Explanation:

The Refrigerant-134a flows into the evaporator as a saturated liquid-vapor mixture and flows out as a saturated vapor at a saturation pressure of 160 kPa and temperature of -15.64°C (estimated from the Saturated Refrigerant-134a Temperature Table).

(a) The entropy change of the refrigerant (ΔS $_{R-134a}$ ) = Q/T $_{1}$

Q = 180 kJ

T $_{1}$ = -15.64 + 273.15 = 257.51 K

ΔS $_{R-134a}$ = Q/T $_{1}$ = 180/257.51 = 0.699 kJ/K

(b) The entropy change (ΔS $_{c}$ ) of the cooled space (ΔS $_{c}$ ) = -Q/T $_{2}$

Q = -180 kJ

T $_{2}$ = -5 + 273.15 = 268.15 K

ΔS $_{c}$ = Q/T $_{2}$ = -180/268.15 = -0.671 kJ/K

(c) The total entropy change for this process (ΔS $_{t}$ ) = ΔS $_{R-134a}$ + ΔS $_{c}$ = 0.699 - 0.671 = 0.028 kJ/K

6 0

4 years ago

You mix 265.0 mL of 1.20 M lead(II) nitrate with 293 mL of 1.55 M potassium iodide. The lead(II) iodide is insoluble. What amoun

slava [35]

Answer:

105 grams PbI₂

Explanation:

Pb(NO₃)₂ + 2KI => 2KNO₃ + PbI₂(s)

moles Pb(NO₃)₂ = 0.265L(1.2M) = 0.318 mole

moles KI = 0.293(1.55M) = 0.454 mole => Limiting Reactant

moles PbI₂ from mole KI in excess Pb(NO₃)₂ = 1/2(0.454 mole) = 0.227 mol PbI₂

grams PbI₂ = 0.227 mol PbI₂ x 461 g/mole = 104.68 g ≈ 105 g PbI₂(s)

7 0

3 years ago

Read 2 more answers

Why is sodium sulphate hemihydrate called as "Plaster of Paris"?

Inga [223]

Do you mean semi-aqueous gypsum calcium?
Is called a semi-aqueous gypsum calcium sulfate, as the formula: CaSO4 * 1/2 H 2 O molecule of water is half (hemihydrate), contains sulfur (sulfate), and calcium (Ca).
Gypsum is a common name because it is used in construction.

3 0

4 years ago

Read 2 more answers

A 500.0-mL buffer solution is 0.100 M in HNO2 and 0.150 M in KNO2. Determine if each addition would exceed the capacity of the b

likoan [24]

Answer:

no one additions exceed the capacity of the buffer

Explanation:

given

Volume buffer = 500.0 mL = 0.5 L

mol HNO₂ = 0.5 L × 0.100 mol/L = 0.05 mol HNO₂

mol NO₂⁻ = 0.5 L × 0.150 mol/L = 0.075 mol NO₂⁻

solution

we know when any base more than 0.05 (HNO2) than exceed buffer capacity

and when any base more than 0.075 (KNO2) than exceed buffer capacity

when we add 250 mg NaOH (0.250 g)

than molar mass NaOH =40 g/mol

and mol NaOH = 0.250 g ÷ 40g/mol

mol NaOH = 0.00625 mol

0.00625 mol NaOH will be neutralized by 0.00625 mol HNO₂

so it would not exceed the capacity of the buffer.

and

when we add 350 mg KOH (0.350 g)

than molar mass KOH =56.10 g

and mol KOH = 0.350 g ÷ 56.10 g/mol

mol KOH = 0.0062 mol

here also capacity of the buffer will not be exceeded

and

now we add 1.25 g HBr

than molar mass HBr = 80.91 g/mol

and mol HBr = 1.25 g ÷ 80.91 g/mol

mol HBr = 0.015 mol

0.015 mol Hbr will neutralize 0.015 mol NO₂⁻

so the capacity will not be exceeded.

and

we add 1.35 g HI

molar mass HI = 127.91 g/mol

so mol HI = 1.35 g ÷ 127.91 g/mol

mol HI = 0.011 mol

capacity of the buffer will not be exceed

3 0

3 years ago