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Alexxx [7]
3 years ago
11

During science lab, some students added small pieces of magnesium ribbon to 10 mL of hydrochloric acid. They noticed that bubble

s formed, the test tube got hot, and the magnesium disappeared.
Which is a sign that a chemical reaction has taken place in this experiment?
Chemistry
2 answers:
stiv31 [10]3 years ago
4 0
Your answer would be a change in odor! Hope this helps! ;D
Stels [109]3 years ago
4 0

Answer:

C

Explanation:

Release of heat energy

The test tube got hot; that's a sign that heat energy is being released. This is an exothermic chemical reaction. Change in odor and color are signs of a chemical change but do not occur in this case.

(Correct in USA Test Prep too!)

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The gauge pressure inside a vessel is ‐40kPa, at an elevation of 5000m. a) What is the absolute pressure? b) At this elevation,
hoa [83]

Answer:

a) Pabs = 48960 KPa

b) T = 433.332 °C

Explanation:

  • Pabs = Pgauge + d*g* h

∴ d = 1000 Kg/m³

∴ g = 9.8 m/s²

∴ h = 5000 m

∴ P gauge = - 40 KPa * ( 1000 Pa / KPa ) = - 40000 Pa; Pa≡Kg/m*s²

⇒ Pabs = - 40000 Kg/ms² + ( 1000 Kg/m³ * 9.8 m/s² * 5000 m )

⇒ Pabs = 48960000 Pa = 48960 KPa

a) at that height and pressure, we find the temperature at which the water boils by means of an almost-exponential graph which has the following equation:

P(T) = 0.61094 exp ( 17.625*T / ( T + 243.04 ))......P (KPa) ∧ T (°C)....from literature

∴ P = 48960 KPa

⇒ ( 48960 KPa / 0.61094 ) = exp ( 17.625T / (T+ 243.04))

⇒ 80138.803 = exp ( 17.625T / ( T + 243.04))

⇒ Ln ( 80138.803) = 17.625T / ( T + 243.04))

⇒ 11.292 * ( T + 243.04 ) = 17.625T

⇒ 11.292T + 2744.289 = 17.625T

⇒ 2744.289 = 17.625T - 11.292T

⇒ 2744.289 = 6.333T

⇒ T = 433.332 °C

3 0
2 years ago
26 Which process occurs in an operating voltaic cell?(1) Electrical energy is converted to chemical energy.
tia_tia [17]

Answer is: (2) Chemical energy is converted to electrical energy.

An electrochemical cell (voltaic or galvanic cell) is generating electrical energy from chemical reactions.

In galvanic cell, specie (for example zinc and zinc cations) from one half-cell, lose electrons (oxidation) and species from the other half-cell (for example copper and copper cations) gain electrons (reduction).

Oxidation on the zinc anode: Zn(s) → Zn²⁺(aq) + 2e⁻.

Reduction on the copper cathode: Cu²⁺(aq) + 2e⁻ → Cu(s).

8 0
3 years ago
Read 2 more answers
HELP PLEASE!! ASAP What would the mass be in kg?
fgiga [73]

Answer:

i guess answer is 0.0600

Explanation:

Here,

Density=0.791g/cm^3

Volume=75.89ml

So,

Mass=Density*Volume

=0.791g/cm^3×75.89ml

=60.02g/cm^3.ml

Expressing them in kg

60.02/1000

=0.0600 kg

4 0
2 years ago
1. The speed limit on most city streets is (25 miles). How many meters per minute
irina1246 [14]

Answer:

Speed = 670.56 \frac{m}{min}

Explanation:

Given

Speed = \frac{25 mi}{hr}

Required

Convert to meters per minutes

Speed = \frac{25 mi}{hr}

Start by converting the speed from miles to meters

1\ mile = 1609.34\ meters.

So, we have:

Speed = \frac{25 * 1609.34\ m}{hr}

Speed = \frac{40233.5\ m}{hr}

Next, we convert time from hours to minutes

1\ hour = 60\ minutes

So, we have:

Speed = \frac{40233.5\ m}{60\ min}

Speed = 670.56 \frac{m}{min}

<em>Hence, the equivalent of 25 miles per hour is 670.56 meters per minutes</em>

3 0
3 years ago
plants need carbon dioxide in order to survive. Plants get this gas from? which is something all organisms need.​
vichka [17]

Answer: sunlight

Explanation:

They get carbon dioxide from the sunlight, in a process called photosynthesis. They absorb the sunlight and turn the energy into carbon dioxide.

6 0
3 years ago
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