The key important thing that you have failed to ask is if the media is reporting the events accurately or in the grossly exaggerated manner that “sells” so-called "news". (And if what you seem to have read or heard previous to this also falls into the category of not-really-accurate.)
There are no “riots” in Brazil. People are protesting, are bringing their young children into the streets with them to march in this historic situation, to try to address the severe and entrenched problems with inadequate schools, corrupt politicians, poor healthcare and other important socio-economic issues in Brazil. The media chooses to focus on the very few troublemakers. And yes, some Brazilians do think that disrupting the life of foreign tourists, as in blocking traffic where they may be in transit, brings these issues to the tourists' attention and embarrasses the government; embarrassment, unfortunately, is not going to cause substantial change by a government that in recent history rewrote the constitution and brought in a dictator, but these particular disruptions have at any rate been minor.
Let me save more time and space and point you toward a similar doubt which came up in the middle of this thread:
Brazil can be quite comfortable to travel around, but a great deal of your safety lies in your own actions and judgement. Larger cities, especially Rio, where the socio-economic differences are wider and more side-by-side, are quite different, as in many parts of the world, from smaller seaside towns/beaches, rural areas and smaller cities/towns, which are more tranquil and relaxed. Plan enough time to explore some of these tranquil and often historic places, as well as Rio.
As a resourceful traveler, travel on your own is quite possible and practical in Brazil, no matter your age or appearance. In the cities, taxis are relatively cheap, safe and easy to find. Airport shuttle buses are often available. The intercity bus system is excellent and very comfortable. Flights are available and safe. You can book your own hotel, pousada, or short-term apartment quite easily on your own, according to your budget.
The issue of using your good judgement, mentioned above, includes deliberately choosing to make yourself stand out, to call unnecessary attention to yourself as rich (you may not think you are, but someone who does hard physical labor for about U$200 a month to support an entire family may disagree), and to place yourself in isolated surroundings to become more vulnerable. If you choose to show items in public that equal what a passerby earns in several months to support his family, this is not using good judgment IMO.
Specifically regarding your expensive camera in Rio, you can take a taxi to the ticketed heights of Corcovado and Sugarloaf (populated only by other tourists), with the camera in a plain plastic Brazilian grocery store bag or similar, take your photos and return by taxi to your hotel. Otherwise, I suggest a small digital camera with a good lens, that you can use discreetly and put away immediately after use. Outside the bigger cities, this is not such an issue.
Let me reassure you that, as a woman of almost your own age who does not look particualrly Brazilian (although Brazilians do come in all "varieties"), I have been traveling around Brazil, often solo, for decades with no incidents to report. The Brazilian people are warm, welcoming and helpful, the true diamonds of any visit.
If you have any further questions, or would like more help planning your Brazil visit, please post again. I would be happy to assist you to discover a country I am passionate about.