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3 years ago

Which step is part of a scientific investigation?

1 answer:

3 0

Steps of a scientific investigation include identifying a research question or problem, forming a hypothesis, gathering evidence, analyzing evidence, deciding whether the evidence supports the hypothesis, drawing conclusions, and communicating the results.

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__Ca(OH)2 + __ (NH4)2SO4 ----- > ___CaSO4 + ___NH3 + __H2O A)11 B)5 C)7 D)9

katovenus [111]

There would be a 2 infront of the NH3 and and 2 Infront of the H2O

6 0

3 years ago

When 0.620 gMngMn is combined with enough hydrochloric acid to make 100.0 mLmL of solution in a coffee-cup calorimeter, all of t

OleMash [197]

Answer:

The enthalpy change during the reaction is -199. kJ/mol.

Explanation:

$Mn(s)+2HCl(aq)\rightarrow MnCl_2(aq)+H_2(g)$

Mass of solution = m

Volume of solution = 100.0 mL

Density of solution = d = 1.00 g/mL

$m=1.00 g/mL\times 100.0 mL = 100 g$

First we have to calculate the heat gained by the solution in coffee-cup calorimeter.

$q=m\times c\times (T_{final}-T_{initial})$

where,

m = mass of solution = 100 g

q = heat gained = ?

c = specific heat = $4.18 J/^oC$

$T_{final}$ = final temperature = $23.1^oC$

$T_{initial}$ = initial temperature = $28.9^oC$

Now put all the given values in the above formula, we get:

$q=100 g \times 4.18 J/^oC\times (28.9-23.1)^oC$

$q=2,242.4 J=2.242 kJ$

Now we have to calculate the enthalpy change during the reaction.

$\Delta H=-\frac{q}{n}$

where,

$\Delta H$ = enthalpy change = ?

q = heat gained = 2.242 kJ

n = number of moles fructose = $\frac{\text{Mass of manganese}}{\text{Molar mass of manganese}}=\frac{0.620 g}{54.94 g/mol}=0.0113 mol$

$\Delta H=-\frac{2.242 kJ}{0.0113 mol }=-199. kJ/mol$

Therefore, the enthalpy change during the reaction is -199. kJ/mol.

8 0

3 years ago

Match each type of reaction to its amount of potential energy. (PLEASE HELP )

sergejj [24]

Endo is more in reactants and exo is more in products because in exothermic reactions heat is released

8 0

3 years ago

Identify if you should use millimeters, centimeters, meters, or kilometers to measure each example.

ira [324]

Answer:

1. unless you live right around the block, distance from home to school should be in kilometers.

2. centimeters

3. millimeters

4. meters (the average is about 2 meters)

3 0

3 years ago

Read 2 more answers

A 20 kg curling stone is sliding in a positive direction at 4 m/s. A second curling stone is sliding at the same speed but in th

solniwko [45]

Answer:

The kinetic energy of the two stones is 320 J

Explanation:

Kinetic energy is the energy that a body possesses due to its movement. So it is the capacity or work that allows an object to go from being at rest, or still, to moving at a certain speed.

In other words, the kinetic energy of an object is that which is produced due to its motion and depends on its mass and velocity as follows:

$Ec=\frac{1}{2} *m*v^{2}$

where the kinetic energy Ec is measured in joules (J), the mass m is measured in kilograms (kg) and the velocity v in meters/second (m/s).

In this case you know that a 20 kg curling stone is sliding in a positive direction at 4 m/s. So:

m= 20 kg
v= 4 m/s

Replacing you have:

$Ec_{1} =\frac{1}{2} *20 kg*(4\frac{m}{s}) ^{2}$

Ec₁= 160 J

A second curling stone slides at the same speed but in the opposite direction. So:

m= 20 kg
v= - 4 m/s

Replacing you have:

$Ec_{2} =\frac{1}{2} *20 kg*(-4\frac{m}{s}) ^{2}$

Ec₂= 160 J

The kinetic energy of the two stones is calculated as:

Ec= Ec₁ + Ec₂

Ec= 160 J + 160 J

Ec= 320 J

The kinetic energy of the two stones is 320 J

7 0

3 years ago