Can someone please help!! I’m in a test!!

Which of the following elements is the least reactive metal? Sodium, Rubidium, Chlorine, and Magnesium.

LuckyWell [14K]

First off chlorine is not a metal so you can ignore that one.

Sodium and Rubidium are in group 1 of the periodic table and Magnesium is in group 2.

Group one metals are more reactive than group two because it is harder for the group two metals to lose their 2 valence (outer most) electrons.

As you go down group 1 there is an increase in the reactivity this is because as you go down there is an increase in the atomic radius which leads to more shielding. This weakens the electrostatic forces of attraction making it easier to lose the outermost electrons, therefore they are more reactive.

6 0

3 years ago

The coordination number of cation and anion in fluorite CaF2 and antifluorite Na2O are respectively

sp2606 [1]

<u>8:4 and 4:8</u> both have CCP structure............................... ᐛ

6 0

3 years ago

What is missing from the temperature and volume graph shown at right?

Kaylis [27]

Answer: Three things are missing:

i) Graph title.

ii) Label for the vertical axis.

iii) The scale and the units for the horizontal axis.

Justification:

1) Find the graph in the image attached.

2) What does the graph represent? You cannot tell because it does not show the tittle.

Since you are told in the statement that it is a temperature and volume graph, the appropiate title would be:

Temperature vs. Volume.

3) The vertical axis also must be properly labeled, including the units.

A good label for the vertical axis of this graph might be: Volume (cm³). It migh also be liters, gallons, or other volume unit.

4) Although the horizontal axis is labeled, it does not indicate the units and the scale. So, you know neither if the temperature shown is celsius, (°C), farenheti (°F), kelvin (K), or rankine (R) (those are the four major scales of temperature), nor how much each division represent (1, 5, 10, 10, 50, 100?)

4 0

4 years ago

Calculate the pH of 1.00 L of a buffer that contains 0.105 M HNO2 and 0.170 M NaNO2. What is the pH of the same buffer after the

kari74 [83]

Answer:

1.- pH =3.61

2.-pH =3.53

Explanation:

In the first part of this problem we can compute the pH of the buffer by making use of the Henderson-Hasselbach equation,

pH = pKa + log [A⁻]/[HA]

where [A⁻] is the conjugate base anion concentration ( [NO₂⁻]), [HA] is the weak acid concentration,[HNO₂].

In the second part, our strategy has to take into account that some of the weak base NO₂⁻ will be consumed by reaction with the very strong acid HCl. Thus, first we will calculate the new concentrations, and then find the new pH similar to the first part.

First Part

pH = 3.40+ log {0.170 /0.105}

pH = 3.61

Second Part

# mol HCl = ( 0.001 L ) x 12.0 mol / L = 0.012

# mol NaNO₂ reacted = 0.012 mol ( 1: 1 reaction)

# mol NaNO₂ initial = 0.170 mol/L x 1 L = 0.170 mol

# mol NaNO₂ remaining = (0.170 - 0.012) mol = 0.158

# mol HNO₂ produced = 0.012 mol

# mol HNO₂ initial = 0.105

# new mol HNO₂ = (0.105 + 0.012) mol = 0.117 mol

Now we are ready to use the Henderson-Hasselbach with the new ration. Notice that we dont have to calculate the concentration (M) since we are using a ratio.

pH = 3.40 + log {0.158/.0117}

pH = 3.53

Notice there is little variation in the pH of the buffer. That is the usefulness of buffers.

4 0

3 years ago

Read 2 more answers

Store bought cake mix is usually left to bake at 350°F in an oven, what would happen to the time it

lesya692 [45]

Answer:

It will reduce

Explanation:

The time it will take to bake the cake will reduce when the temperature is increased by an additional 20°F .

Temperature change has a considerable effect on reaction rates since temperature is directly proportional to the average kinetic energy of reacting particles.

Generally reaction rate varies as temperature directly.

Therefore, the baking time will reduce as temperature increases.

4 0

3 years ago